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Merge branch 'develop' into type-labels

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This commit is contained in:
Jacob Gissinger
2022-03-23 01:08:35 -04:00
committed by GitHub
parent 44522221ad 3e7de83e6e
commit e13a70ad2f
3143 changed files with 258487 additions and 425132 deletions
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6
.gitattributes vendored
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@ -3,3 +3,9 @@
.github export-ignore
.lgtm.yml export-ignore
SECURITY.md export-ignore
* text=auto
*.jpg -text
*.pdf -text
*.gz -text
*.png -text
*.ps -text

17
.github/workflows/compile-msvc.yml vendored
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@ -1,5 +1,5 @@
# GitHub action to build LAMMPS on Windows with Visual C++
name: "Native Windows Compilation"
name: "Native Windows Compilation and Unit Tests"
on:
push:
@ -17,13 +17,21 @@ jobs:
with:
fetch-depth: 2
- name: Select Python version
uses: actions/setup-python@v2
with:
python-version: '3.10'
- name: Building LAMMPS via CMake
shell: bash
run: |
python3 -m pip install numpy
cmake -C cmake/presets/windows.cmake \
-D PKG_PYTHON=on \
-S cmake -B build \
-D BUILD_SHARED_LIBS=on \
-D LAMMPS_EXCEPTIONS=on
-D LAMMPS_EXCEPTIONS=on \
-D ENABLE_TESTING=on
cmake --build build --config Release
- name: Run LAMMPS executable
@ -31,3 +39,8 @@ jobs:
run: |
./build/Release/lmp.exe -h
./build/Release/lmp.exe -in bench/in.lj
- name: Run Unit Tests
working-directory: build
shell: bash
run: ctest -V -C Release

1
.gitignore vendored
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@ -12,6 +12,7 @@
*.sif
*.dll
*.pyc
*.whl
a.out
__pycache__

59
cmake/CMakeLists.txt
View File

@ -16,9 +16,13 @@ endif()
project(lammps CXX)
set(SOVERSION 0)
get_property(BUILD_IS_MULTI_CONFIG GLOBAL PROPERTY GENERATOR_IS_MULTI_CONFIG)
get_filename_component(LAMMPS_DIR ${CMAKE_CURRENT_SOURCE_DIR}/.. ABSOLUTE)
get_filename_component(LAMMPS_LIB_BINARY_DIR ${CMAKE_BINARY_DIR}/lib ABSOLUTE)
# collect all executables and shared libs in the top level build folder
set(CMAKE_RUNTIME_OUTPUT_DIRECTORY ${CMAKE_BINARY_DIR})
set(CMAKE_LIBRARY_OUTPUT_DIRECTORY ${CMAKE_BINARY_DIR})
set(LAMMPS_SOURCE_DIR ${LAMMPS_DIR}/src)
set(LAMMPS_LIB_SOURCE_DIR ${LAMMPS_DIR}/lib)
@ -280,36 +284,20 @@ if(BUILD_MPI)
# We use a non-standard procedure to cross-compile with MPI on Windows
if((CMAKE_SYSTEM_NAME STREQUAL "Windows") AND CMAKE_CROSSCOMPILING)
include(MPI4WIN)
target_link_libraries(lammps PUBLIC MPI::MPI_CXX)
else()
find_package(MPI REQUIRED)
target_link_libraries(lammps PUBLIC MPI::MPI_CXX)
option(LAMMPS_LONGLONG_TO_LONG "Workaround if your system or MPI version does not recognize 'long long' data types" OFF)
if(LAMMPS_LONGLONG_TO_LONG)
target_compile_definitions(lammps PRIVATE -DLAMMPS_LONGLONG_TO_LONG)
endif()
endif()
target_link_libraries(lammps PUBLIC MPI::MPI_CXX)
else()
file(GLOB MPI_SOURCES ${LAMMPS_SOURCE_DIR}/STUBS/mpi.cpp)
add_library(mpi_stubs STATIC ${MPI_SOURCES})
set_target_properties(mpi_stubs PROPERTIES OUTPUT_NAME lammps_mpi_stubs${LAMMPS_MACHINE})
target_include_directories(mpi_stubs PUBLIC $<BUILD_INTERFACE:${LAMMPS_SOURCE_DIR}/STUBS>)
if(BUILD_SHARED_LIBS)
target_link_libraries(lammps PRIVATE mpi_stubs)
if(MSVC)
target_link_libraries(lmp PRIVATE mpi_stubs)
target_include_directories(lmp INTERFACE $<BUILD_INTERFACE:${LAMMPS_SOURCE_DIR}/STUBS>)
target_compile_definitions(lmp INTERFACE $<INSTALL_INTERFACE:LAMMPS_LIB_NO_MPI>)
endif()
target_include_directories(lammps INTERFACE $<BUILD_INTERFACE:${LAMMPS_SOURCE_DIR}/STUBS>)
target_compile_definitions(lammps INTERFACE $<INSTALL_INTERFACE:LAMMPS_LIB_NO_MPI>)
else()
target_include_directories(lammps INTERFACE $<BUILD_INTERFACE:${LAMMPS_SOURCE_DIR}/STUBS>)
target_compile_definitions(lammps INTERFACE $<INSTALL_INTERFACE:LAMMPS_LIB_NO_MPI>)
target_sources(lammps PRIVATE ${LAMMPS_SOURCE_DIR}/STUBS/mpi.cpp)
add_library(mpi_stubs INTERFACE)
target_include_directories(mpi_stubs INTERFACE $<BUILD_INTERFACE:${LAMMPS_SOURCE_DIR}/STUBS>)
target_link_libraries(lammps PUBLIC mpi_stubs)
endif()
add_library(MPI::MPI_CXX ALIAS mpi_stubs)
endif()
set(LAMMPS_SIZES "smallbig" CACHE STRING "LAMMPS integer sizes (smallsmall: all 32-bit, smallbig: 64-bit #atoms #timesteps, bigbig: also 64-bit imageint, 64-bit atom ids)")
set(LAMMPS_SIZES_VALUES smallbig bigbig smallsmall)
@ -339,7 +327,6 @@ pkg_depends(ML-IAP ML-SNAP)
pkg_depends(MPIIO MPI)
pkg_depends(ATC MANYBODY)
pkg_depends(LATBOLTZ MPI)
pkg_depends(PHONON KSPACE)
pkg_depends(SCAFACOS MPI)
pkg_depends(DIELECTRIC KSPACE)
pkg_depends(DIELECTRIC EXTRA-PAIR)
@ -373,11 +360,13 @@ if(BUILD_OMP)
((CMAKE_CXX_COMPILER_ID STREQUAL "Intel") AND (CMAKE_CXX_COMPILER_VERSION VERSION_GREATER_EQUAL 19.0)))
# GCC 9.x and later plus Clang 10.x and later implement strict OpenMP 4.0 semantics for consts.
# Intel 18.0 was tested to support both, so we switch to OpenMP 4+ from 19.x onward to be safe.
target_compile_definitions(lammps PRIVATE -DLAMMPS_OMP_COMPAT=4)
set(LAMMPS_OMP_COMPAT_LEVEL 4)
else()
target_compile_definitions(lammps PRIVATE -DLAMMPS_OMP_COMPAT=3)
set(LAMMPS_OMP_COMPAT_LEVEL 3)
endif()
target_compile_definitions(lammps PRIVATE -DLAMMPS_OMP_COMPAT=${LAMMPS_OMP_COMPAT_LEVEL})
target_link_libraries(lammps PRIVATE OpenMP::OpenMP_CXX)
target_link_libraries(lmp PRIVATE OpenMP::OpenMP_CXX)
endif()
if(PKG_MSCG OR PKG_ATC OR PKG_AWPMD OR PKG_ML-QUIP OR PKG_LATTE)
@ -591,11 +580,10 @@ if(PKG_ATC)
if(LAMMPS_SIZES STREQUAL "BIGBIG")
message(FATAL_ERROR "The ATC Package is not compatible with -DLAMMPS_BIGBIG")
endif()
target_link_libraries(atc PRIVATE ${LAPACK_LIBRARIES})
if(BUILD_MPI)
target_link_libraries(atc PRIVATE MPI::MPI_CXX)
target_link_libraries(atc PRIVATE ${LAPACK_LIBRARIES} MPI::MPI_CXX)
else()
target_link_libraries(atc PRIVATE mpi_stubs)
target_link_libraries(atc PRIVATE ${LAPACK_LIBRARIES} mpi_stubs)
endif()
target_include_directories(atc PRIVATE ${LAMMPS_SOURCE_DIR})
target_compile_definitions(atc PRIVATE -DLAMMPS_${LAMMPS_SIZES})
@ -609,7 +597,7 @@ endif()
# packages which selectively include variants based on enabled styles
# e.g. accelerator packages
######################################################################
foreach(PKG_WITH_INCL CORESHELL QEQ OPENMP DPD-SMOOTH KOKKOS OPT INTEL GPU)
foreach(PKG_WITH_INCL CORESHELL DPD-SMOOTH PHONON QEQ OPENMP KOKKOS OPT INTEL GPU)
if(PKG_${PKG_WITH_INCL})
include(Packages/${PKG_WITH_INCL})
endif()
@ -691,6 +679,7 @@ endif()
set_target_properties(lammps PROPERTIES OUTPUT_NAME lammps${LAMMPS_MACHINE})
set_target_properties(lammps PROPERTIES SOVERSION ${SOVERSION})
set_target_properties(lammps PROPERTIES PREFIX "lib")
target_include_directories(lammps PUBLIC $<INSTALL_INTERFACE:${CMAKE_INSTALL_INCLUDEDIR}/lammps>)
file(MAKE_DIRECTORY ${CMAKE_CURRENT_BINARY_DIR}/includes/lammps)
foreach(_HEADER ${LAMMPS_CXX_HEADERS})
@ -710,6 +699,9 @@ foreach(_DEF ${LAMMPS_DEFINES})
endforeach()
if(BUILD_SHARED_LIBS)
install(TARGETS lammps EXPORT LAMMPS_Targets LIBRARY DESTINATION ${CMAKE_INSTALL_LIBDIR} ARCHIVE DESTINATION ${CMAKE_INSTALL_LIBDIR})
if(NOT BUILD_MPI)
install(TARGETS mpi_stubs EXPORT LAMMPS_Targets LIBRARY DESTINATION ${CMAKE_INSTALL_LIBDIR} ARCHIVE DESTINATION ${CMAKE_INSTALL_LIBDIR})
endif()
configure_file(pkgconfig/liblammps.pc.in ${CMAKE_CURRENT_BINARY_DIR}/liblammps${LAMMPS_MACHINE}.pc @ONLY)
install(FILES ${CMAKE_CURRENT_BINARY_DIR}/liblammps${LAMMPS_MACHINE}.pc DESTINATION ${CMAKE_INSTALL_LIBDIR}/pkgconfig)
install(EXPORT LAMMPS_Targets FILE LAMMPS_Targets.cmake NAMESPACE LAMMPS:: DESTINATION ${CMAKE_INSTALL_LIBDIR}/cmake/LAMMPS)
@ -749,7 +741,7 @@ install(
if(BUILD_SHARED_LIBS)
if(CMAKE_VERSION VERSION_LESS 3.12)
# adjust so we find Python 3 versions before Python 2 on old systems with old CMake
set(Python_ADDITIONAL_VERSIONS 3.9 3.8 3.7 3.6 3.5)
set(Python_ADDITIONAL_VERSIONS 3.12 3.11 3.10 3.9 3.8 3.7 3.6)
find_package(PythonInterp) # Deprecated since version 3.12
if(PYTHONINTERP_FOUND)
set(Python_EXECUTABLE ${PYTHON_EXECUTABLE})
@ -757,13 +749,15 @@ if(BUILD_SHARED_LIBS)
else()
find_package(Python COMPONENTS Interpreter)
endif()
if(BUILD_IS_MULTI_CONFIG)
set(LIBLAMMPS_SHARED_BINARY ${CMAKE_BINARY_DIR}/$<CONFIG>/liblammps${LAMMPS_MACHINE}${CMAKE_SHARED_LIBRARY_SUFFIX})
else()
set(LIBLAMMPS_SHARED_BINARY ${CMAKE_BINARY_DIR}/liblammps${LAMMPS_MACHINE}${CMAKE_SHARED_LIBRARY_SUFFIX})
endif()
if(Python_EXECUTABLE)
add_custom_target(
install-python ${CMAKE_COMMAND} -E remove_directory build
COMMAND ${Python_EXECUTABLE} install.py -v ${LAMMPS_SOURCE_DIR}/version.h
-p ${LAMMPS_PYTHON_DIR}/lammps
-l ${CMAKE_BINARY_DIR}/liblammps${LAMMPS_MACHINE}${CMAKE_SHARED_LIBRARY_SUFFIX}
WORKING_DIRECTORY ${LAMMPS_PYTHON_DIR}
COMMAND ${Python_EXECUTABLE} ${LAMMPS_PYTHON_DIR}/install.py -p ${LAMMPS_PYTHON_DIR}/lammps -l ${LIBLAMMPS_SHARED_BINARY}
COMMENT "Installing LAMMPS Python module")
else()
add_custom_target(
@ -808,7 +802,6 @@ if(ClangFormat_FOUND)
endif()
get_target_property(DEFINES lammps COMPILE_DEFINITIONS)
get_property(BUILD_IS_MULTI_CONFIG GLOBAL PROPERTY GENERATOR_IS_MULTI_CONFIG)
if(BUILD_IS_MULTI_CONFIG)
set(LAMMPS_BUILD_TYPE "Multi-Config")
else()

97
cmake/CMakeSettings.json
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@ -6,7 +6,7 @@
"configurationType": "Debug",
"buildRoot": "${workspaceRoot}\\build\\${name}",
"installRoot": "${workspaceRoot}\\install\\${name}",
"cmakeCommandArgs": "-S ${workspaceRoot}\\cmake -C ${workspaceRoot}\\cmake\\presets\\windows.cmake -DENABLE_TESTING=on",
"cmakeCommandArgs": "-C ${workspaceRoot}\\cmake\\presets\\windows.cmake",
"buildCommandArgs": "",
"ctestCommandArgs": "",
"inheritEnvironments": [ "msvc_x64_x64" ],
@ -25,6 +25,54 @@
"name": "LAMMPS_EXCEPTIONS",
"value": "True",
"type": "BOOL"
},
{
"name": "PKG_PYTHON",
"value": "True",
"type": "BOOL"
},
{
"name": "ENABLE_TESTING",
"value": "True",
"type": "BOOL"
}
]
},
{
"name": "x64-Release-MSVC",
"generator": "Ninja",
"configurationType": "Release",
"buildRoot": "${workspaceRoot}\\build\\${name}",
"installRoot": "${workspaceRoot}\\install\\${name}",
"cmakeCommandArgs": "-C ${workspaceRoot}\\cmake\\presets\\windows.cmake",
"buildCommandArgs": "",
"ctestCommandArgs": "",
"inheritEnvironments": [ "msvc_x64_x64" ],
"variables": [
{
"name": "BUILD_SHARED_LIBS",
"value": "True",
"type": "BOOL"
},
{
"name": "BUILD_TOOLS",
"value": "True",
"type": "BOOL"
},
{
"name": "LAMMPS_EXCEPTIONS",
"value": "True",
"type": "BOOL"
},
{
"name": "PKG_PYTHON",
"value": "True",
"type": "BOOL"
},
{
"name": "ENABLE_TESTING",
"value": "True",
"type": "BOOL"
}
]
},
@ -34,11 +82,16 @@
"configurationType": "Debug",
"buildRoot": "${workspaceRoot}\\build\\${name}",
"installRoot": "${workspaceRoot}\\install\\${name}",
"cmakeCommandArgs": "-S ${workspaceRoot}\\cmake -C ${workspaceRoot}\\cmake\\presets\\windows.cmake -DENABLE_TESTING=on",
"cmakeCommandArgs": "-C ${workspaceRoot}\\cmake\\presets\\windows.cmake -DCMAKE_C_COMPILER=clang-cl.exe -DCMAKE_CXX_COMPILER=clang-cl.exe",
"buildCommandArgs": "",
"ctestCommandArgs": "",
"inheritEnvironments": [ "clang_cl_x64" ],
"variables": [
{
"name": "BUILD_SHARED_LIBS",
"value": "True",
"type": "BOOL"
},
{
"name": "BUILD_TOOLS",
"value": "True",
@ -48,19 +101,29 @@
"name": "LAMMPS_EXCEPTIONS",
"value": "True",
"type": "BOOL"
},
{
"name": "PKG_PYTHON",
"value": "True",
"type": "BOOL"
},
{
"name": "ENABLE_TESTING",
"value": "True",
"type": "BOOL"
}
]
},
{
"name": "x64-Debug-OneAPI",
"name": "x64-Release-Clang",
"generator": "Ninja",
"configurationType": "Debug",
"configurationType": "Release",
"buildRoot": "${workspaceRoot}\\build\\${name}",
"installRoot": "${workspaceRoot}\\install\\${name}",
"cmakeCommandArgs": "-S ${workspaceRoot}\\cmake -C ${workspaceRoot}\\cmake\\presets\\windows.cmake -DENABLE_TESTING=on -DCMAKE_CXX_COMPILER=icx -DCMAKE_C_COMPILER=icx -DBUILD_MPI=off",
"cmakeCommandArgs": "-C ${workspaceRoot}\\cmake\\presets\\windows.cmake -DCMAKE_C_COMPILER=clang-cl.exe -DCMAKE_CXX_COMPILER=clang-cl.exe",
"buildCommandArgs": "",
"ctestCommandArgs": "",
"inheritEnvironments": [ "msvc_x64_x64" ],
"inheritEnvironments": [ "clang_cl_x64" ],
"variables": [
{
"name": "BUILD_SHARED_LIBS",
@ -76,32 +139,14 @@
"name": "LAMMPS_EXCEPTIONS",
"value": "True",
"type": "BOOL"
}
]
},
{
"name": "x64-Debug-Intel",
"generator": "Ninja",
"configurationType": "Debug",
"buildRoot": "${workspaceRoot}\\build\\${name}",
"installRoot": "${workspaceRoot}\\install\\${name}",
"cmakeCommandArgs": "-S ${workspaceRoot}\\cmake -C ${workspaceRoot}\\cmake\\presets\\windows.cmake -DENABLE_TESTING=off -DCMAKE_CXX_COMPILER=icl -DCMAKE_C_COMPILER=icl -DCMAKE_Fortran_COMPILER=ifort -DBUILD_MPI=off",
"buildCommandArgs": "",
"ctestCommandArgs": "",
"inheritEnvironments": [ "msvc_x64_x64" ],
"variables": [
{
"name": "BUILD_SHARED_LIBS",
"name": "PKG_PYTHON",
"value": "True",
"type": "BOOL"
},
{
"name": "BUILD_TOOLS",
"value": "True",
"type": "BOOL"
},
{
"name": "LAMMPS_EXCEPTIONS",
"name": "ENABLE_TESTING",
"value": "True",
"type": "BOOL"
}

9
cmake/Modules/FindCythonize.cmake
View File

@ -8,18 +8,19 @@
#=============================================================================
if(CMAKE_VERSION VERSION_LESS 3.12)
set(Python_ADDITIONAL_VERSIONS 3.12 3.11 3.10 3.9 3.8 3.7 3.6)
find_package(PythonInterp 3.6 QUIET) # Deprecated since version 3.12
if(PYTHONINTERP_FOUND)
set(Python3_EXECUTABLE ${PYTHON_EXECUTABLE})
set(Python_EXECUTABLE ${PYTHON_EXECUTABLE})
endif()
else()
find_package(Python3 3.6 COMPONENTS Interpreter QUIET)
find_package(Python 3.6 COMPONENTS Interpreter QUIET)
endif()
# Use the Cython executable that lives next to the Python executable
# if it is a local installation.
if(Python3_EXECUTABLE)
get_filename_component(_python_path ${Python3_EXECUTABLE} PATH)
if(Python_EXECUTABLE)
get_filename_component(_python_path ${Python_EXECUTABLE} PATH)
find_program(Cythonize_EXECUTABLE
NAMES cythonize3 cythonize cythonize.bat
HINTS ${_python_path})

2
cmake/Modules/LAMMPSUtils.cmake
View File

@ -25,7 +25,7 @@ function(validate_option name values)
endfunction(validate_option)
function(get_lammps_version version_header variable)
file(READ ${version_header} line)
file(STRINGS ${version_header} line REGEX LAMMPS_VERSION)
set(MONTHS x Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec)
string(REGEX REPLACE "#define LAMMPS_VERSION \"([0-9]+) ([A-Za-z]+) ([0-9]+)\"" "\\1" day "${line}")
string(REGEX REPLACE "#define LAMMPS_VERSION \"([0-9]+) ([A-Za-z]+) ([0-9]+)\"" "\\2" month "${line}")

51
cmake/Modules/OpenCLLoader.cmake
View File

@ -1,50 +1,11 @@
message(STATUS "Downloading and building OpenCL loader library")
set(OPENCL_LOADER_URL "${LAMMPS_THIRDPARTY_URL}/opencl-loader-2021.09.18.tar.gz" CACHE STRING "URL for OpenCL loader tarball")
set(OPENCL_LOADER_MD5 "3b3882627964bd02e5c3b02065daac3c" CACHE STRING "MD5 checksum of OpenCL loader tarball")
set(OPENCL_LOADER_URL "${LAMMPS_THIRDPARTY_URL}/opencl-loader-2022.01.04.tar.gz" CACHE STRING "URL for OpenCL loader tarball")
set(OPENCL_LOADER_MD5 "8d3a801e87a2c6653bf0e27707063914" CACHE STRING "MD5 checksum of OpenCL loader tarball")
mark_as_advanced(OPENCL_LOADER_URL)
mark_as_advanced(OPENCL_LOADER_MD5)
include(ExternalProject)
ExternalProject_Add(opencl_loader
URL ${OPENCL_LOADER_URL}
URL_MD5 ${OPENCL_LOADER_MD5}
SOURCE_DIR "${CMAKE_BINARY_DIR}/opencl_loader-src"
BINARY_DIR "${CMAKE_BINARY_DIR}/opencl_loader-build"
CMAKE_ARGS ${CMAKE_REQUEST_PIC} ${CMAKE_EXTRA_OPENCL_LOADER_OPTS}
-DCMAKE_CXX_COMPILER=${CMAKE_CXX_COMPILER}
-DCMAKE_INSTALL_PREFIX=<INSTALL_DIR>
-DCMAKE_BUILD_TYPE=${CMAKE_BUILD_TYPE}
-DCMAKE_MAKE_PROGRAM=${CMAKE_MAKE_PROGRAM}
-DCMAKE_TOOLCHAIN_FILE=${CMAKE_TOOLCHAIN_FILE}
BUILD_BYPRODUCTS <BINARY_DIR>/libOpenCL${CMAKE_STATIC_LIBRARY_SUFFIX}
LOG_DOWNLOAD ON
LOG_CONFIGURE ON
LOG_BUILD ON
INSTALL_COMMAND ""
TEST_COMMAND "")
ExternalProject_Get_Property(opencl_loader SOURCE_DIR)
set(OPENCL_LOADER_INCLUDE_DIR ${SOURCE_DIR}/inc)
# workaround for CMake 3.10 on ubuntu 18.04
file(MAKE_DIRECTORY ${OPENCL_LOADER_INCLUDE_DIR})
ExternalProject_Get_Property(opencl_loader BINARY_DIR)
set(OPENCL_LOADER_LIBRARY_PATH "${BINARY_DIR}/libOpenCL${CMAKE_STATIC_LIBRARY_SUFFIX}")
find_package(Threads QUIET)
if(NOT WIN32)
set(OPENCL_LOADER_DEP_LIBS "Threads::Threads;${CMAKE_DL_LIBS}")
else()
set(OPENCL_LOADER_DEP_LIBS "cfgmgr32;runtimeobject")
endif()
add_library(OpenCL::OpenCL UNKNOWN IMPORTED)
add_dependencies(OpenCL::OpenCL opencl_loader)
set_target_properties(OpenCL::OpenCL PROPERTIES
IMPORTED_LOCATION ${OPENCL_LOADER_LIBRARY_PATH}
INTERFACE_INCLUDE_DIRECTORIES ${OPENCL_LOADER_INCLUDE_DIR}
INTERFACE_LINK_LIBRARIES "${OPENCL_LOADER_DEP_LIBS}")
set(INSTALL_LIBOPENCL OFF CACHE BOOL "" FORCE)
include(ExternalCMakeProject)
ExternalCMakeProject(opencl_loader ${OPENCL_LOADER_URL} ${OPENCL_LOADER_MD5} opencl-loader . "")
add_library(OpenCL::OpenCL ALIAS OpenCL)

5
cmake/Modules/Packages/COMPRESS.cmake
View File

@ -1,10 +1,11 @@
find_package(ZLIB REQUIRED)
target_link_libraries(lammps PRIVATE ZLIB::ZLIB)
find_package(PkgConfig REQUIRED)
find_package(PkgConfig QUIET)
if(PkgConfig_FOUND)
pkg_check_modules(Zstd IMPORTED_TARGET libzstd>=1.4)
if(Zstd_FOUND)
target_compile_definitions(lammps PRIVATE -DLAMMPS_ZSTD)
target_link_libraries(lammps PRIVATE PkgConfig::Zstd)
endif()
endif()

21
cmake/Modules/Packages/GPU.cmake
View File

@ -30,7 +30,15 @@ file(GLOB GPU_LIB_SOURCES ${LAMMPS_LIB_SOURCE_DIR}/gpu/[^.]*.cpp)
file(MAKE_DIRECTORY ${LAMMPS_LIB_BINARY_DIR}/gpu)
if(GPU_API STREQUAL "CUDA")
find_package(CUDA QUIET)
# augment search path for CUDA toolkit libraries to include the stub versions. Needed to find libcuda.so on machines without a CUDA driver installation
if(CUDA_FOUND)
set(CMAKE_LIBRARY_PATH "${CUDA_TOOLKIT_ROOT_DIR}/lib64/stubs;${CUDA_TOOLKIT_ROOT_DIR}/lib/stubs;${CUDA_TOOLKIT_ROOT_DIR}/lib64;${CUDA_TOOLKIT_ROOT_DIR}/lib;${CMAKE_LIBRARY_PATH}")
find_package(CUDA REQUIRED)
else()
message(FATAL_ERROR "CUDA Toolkit not found")
endif()
find_program(BIN2C bin2c)
if(NOT BIN2C)
message(FATAL_ERROR "Could not find bin2c, use -DBIN2C=/path/to/bin2c to help cmake finding it.")
@ -306,12 +314,12 @@ elseif(GPU_API STREQUAL "HIP")
if(HIP_COMPILER STREQUAL "clang")
add_custom_command(OUTPUT ${CUBIN_FILE}
VERBATIM COMMAND ${HIP_HIPCC_EXECUTABLE} --genco --offload-arch=${HIP_ARCH} -O3 -ffast-math -DUSE_HIP -D_${GPU_PREC_SETTING} -DLAMMPS_${LAMMPS_SIZES} -I${LAMMPS_LIB_SOURCE_DIR}/gpu -o ${CUBIN_FILE} ${CU_CPP_FILE}
VERBATIM COMMAND ${HIP_HIPCC_EXECUTABLE} --genco --offload-arch=${HIP_ARCH} -O3 -DUSE_HIP -D_${GPU_PREC_SETTING} -DLAMMPS_${LAMMPS_SIZES} -I${LAMMPS_LIB_SOURCE_DIR}/gpu -o ${CUBIN_FILE} ${CU_CPP_FILE}
DEPENDS ${CU_CPP_FILE}
COMMENT "Generating ${CU_NAME}.cubin")
else()
add_custom_command(OUTPUT ${CUBIN_FILE}
VERBATIM COMMAND ${HIP_HIPCC_EXECUTABLE} --genco -t="${HIP_ARCH}" -f=\"-O3 -ffast-math -DUSE_HIP -D_${GPU_PREC_SETTING} -DLAMMPS_${LAMMPS_SIZES} -I${LAMMPS_LIB_SOURCE_DIR}/gpu\" -o ${CUBIN_FILE} ${CU_CPP_FILE}
VERBATIM COMMAND ${HIP_HIPCC_EXECUTABLE} --genco -t="${HIP_ARCH}" -f=\"-O3 -DUSE_HIP -D_${GPU_PREC_SETTING} -DLAMMPS_${LAMMPS_SIZES} -I${LAMMPS_LIB_SOURCE_DIR}/gpu\" -o ${CUBIN_FILE} ${CU_CPP_FILE}
DEPENDS ${CU_CPP_FILE}
COMMENT "Generating ${CU_NAME}.cubin")
endif()
@ -422,13 +430,12 @@ RegisterStylesExt(${GPU_SOURCES_DIR} gpu GPU_SOURCES)
RegisterFixStyle(${GPU_SOURCES_DIR}/fix_gpu.h)
get_property(GPU_SOURCES GLOBAL PROPERTY GPU_SOURCES)
if(NOT BUILD_MPI)
# mpistubs is aliased to MPI::MPI_CXX, but older versions of cmake won't work forward the include path
target_link_libraries(gpu PRIVATE mpi_stubs)
else()
if(BUILD_MPI)
target_link_libraries(gpu PRIVATE MPI::MPI_CXX)
else()
target_link_libraries(gpu PRIVATE mpi_stubs)
endif()
target_compile_definitions(gpu PRIVATE -DLAMMPS_${LAMMPS_SIZES})
set_target_properties(gpu PROPERTIES OUTPUT_NAME lammps_gpu${LAMMPS_MACHINE})
target_sources(lammps PRIVATE ${GPU_SOURCES})

44
cmake/Modules/Packages/KOKKOS.cmake
View File

@ -11,8 +11,14 @@ if(Kokkos_ENABLE_CUDA)
endif()
# Adding OpenMP compiler flags without the checks done for
# BUILD_OMP can result in compile failures. Enforce consistency.
if(Kokkos_ENABLE_OPENMP AND NOT BUILD_OMP)
if(Kokkos_ENABLE_OPENMP)
if(NOT BUILD_OMP)
message(FATAL_ERROR "Must enable BUILD_OMP with Kokkos_ENABLE_OPENMP")
else()
if(LAMMPS_OMP_COMPAT_LEVEL LESS 4)
message(FATAL_ERROR "Compiler must support OpenMP 4.0 or later with Kokkos_ENABLE_OPENMP")
endif()
endif()
endif()
########################################################################
@ -27,6 +33,8 @@ if(DOWNLOAD_KOKKOS)
endforeach()
message(STATUS "KOKKOS download requested - we will build our own")
list(APPEND KOKKOS_LIB_BUILD_ARGS "-DCMAKE_INSTALL_PREFIX=<INSTALL_DIR>")
# build KOKKOS downloaded libraries as static libraries but with PIC, if needed
list(APPEND KOKKOS_LIB_BUILD_ARGS "-DBUILD_SHARED_LIBS=OFF")
if(CMAKE_REQUEST_PIC)
list(APPEND KOKKOS_LIB_BUILD_ARGS ${CMAKE_REQUEST_PIC})
endif()
@ -47,18 +55,22 @@ if(DOWNLOAD_KOKKOS)
URL ${KOKKOS_URL}
URL_MD5 ${KOKKOS_MD5}
CMAKE_ARGS ${KOKKOS_LIB_BUILD_ARGS}
BUILD_BYPRODUCTS <INSTALL_DIR>/lib/libkokkoscore.a
BUILD_BYPRODUCTS <INSTALL_DIR>/lib/libkokkoscore.a <INSTALL_DIR>/lib/libkokkoscontainers.a
)
ExternalProject_get_property(kokkos_build INSTALL_DIR)
file(MAKE_DIRECTORY ${INSTALL_DIR}/include)
add_library(LAMMPS::KOKKOS UNKNOWN IMPORTED)
set_target_properties(LAMMPS::KOKKOS PROPERTIES
add_library(LAMMPS::KOKKOSCORE UNKNOWN IMPORTED)
add_library(LAMMPS::KOKKOSCONTAINERS UNKNOWN IMPORTED)
set_target_properties(LAMMPS::KOKKOSCORE PROPERTIES
IMPORTED_LOCATION "${INSTALL_DIR}/lib/libkokkoscore.a"
INTERFACE_INCLUDE_DIRECTORIES "${INSTALL_DIR}/include"
INTERFACE_LINK_LIBRARIES ${CMAKE_DL_LIBS})
target_link_libraries(lammps PRIVATE LAMMPS::KOKKOS)
target_link_libraries(lmp PRIVATE LAMMPS::KOKKOS)
add_dependencies(LAMMPS::KOKKOS kokkos_build)
set_target_properties(LAMMPS::KOKKOSCONTAINERS PROPERTIES
IMPORTED_LOCATION "${INSTALL_DIR}/lib/libkokkoscontainers.a")
target_link_libraries(lammps PRIVATE LAMMPS::KOKKOSCORE LAMMPS::KOKKOSCONTAINERS)
target_link_libraries(lmp PRIVATE LAMMPS::KOKKOSCORE LAMMPS::KOKKOSCONTAINERS)
add_dependencies(LAMMPS::KOKKOSCORE kokkos_build)
add_dependencies(LAMMPS::KOKKOSCONTAINERS kokkos_build)
elseif(EXTERNAL_KOKKOS)
find_package(Kokkos 3.5.00 REQUIRED CONFIG)
target_link_libraries(lammps PRIVATE Kokkos::kokkos)
@ -66,8 +78,17 @@ elseif(EXTERNAL_KOKKOS)
else()
set(LAMMPS_LIB_KOKKOS_SRC_DIR ${LAMMPS_LIB_SOURCE_DIR}/kokkos)
set(LAMMPS_LIB_KOKKOS_BIN_DIR ${LAMMPS_LIB_BINARY_DIR}/kokkos)
# build KOKKOS internal libraries as static libraries but with PIC, if needed
if(BUILD_SHARED_LIBS)
set(BUILD_SHARED_LIBS_WAS_ON YES)
set(BUILD_SHARED_LIBS OFF)
endif()
if(CMAKE_REQUEST_PIC)
set(CMAKE_POSITION_INDEPENDENT_CODE ON)
endif()
add_subdirectory(${LAMMPS_LIB_KOKKOS_SRC_DIR} ${LAMMPS_LIB_KOKKOS_BIN_DIR})
set(Kokkos_INCLUDE_DIRS ${LAMMPS_LIB_KOKKOS_SRC_DIR}/core/src
${LAMMPS_LIB_KOKKOS_SRC_DIR}/containers/src
${LAMMPS_LIB_KOKKOS_SRC_DIR}/algorithms/src
@ -75,6 +96,9 @@ else()
target_include_directories(lammps PRIVATE ${Kokkos_INCLUDE_DIRS})
target_link_libraries(lammps PRIVATE kokkos)
target_link_libraries(lmp PRIVATE kokkos)
if(BUILD_SHARED_LIBS_WAS_ON)
set(BUILD_SHARED_LIBS ON)
endif()
endif()
target_compile_definitions(lammps PUBLIC $<BUILD_INTERFACE:LMP_KOKKOS>)
@ -109,6 +133,12 @@ if(PKG_KSPACE)
endif()
endif()
if(PKG_PHONON)
list(APPEND KOKKOS_PKG_SOURCES ${KOKKOS_PKG_SOURCES_DIR}/dynamical_matrix_kokkos.cpp)
list(APPEND KOKKOS_PKG_SOURCES ${KOKKOS_PKG_SOURCES_DIR}/third_order_kokkos.cpp)
endif()
set_property(GLOBAL PROPERTY "KOKKOS_PKG_SOURCES" "${KOKKOS_PKG_SOURCES}")
# detects styles which have KOKKOS version

6
cmake/Modules/Packages/ML-HDNNP.cmake
View File

@ -46,12 +46,10 @@ if(DOWNLOAD_N2P2)
if((CMAKE_SYSTEM_NAME STREQUAL Windows) AND CMAKE_CROSSCOMPILING)
get_target_property(N2P2_MPI_INCLUDE MPI::MPI_CXX INTERFACE_INCLUDE_DIRECTORIES)
set(N2P2_PROJECT_OPTIONS "-I${N2P2_MPI_INCLUDE}")
set(MPI_CXX_COMPILER ${CMAKE_CXX_COMPILER})
endif()
if(CMAKE_CXX_COMPILER_ID STREQUAL "Intel")
get_target_property(N2P2_MPI_INCLUDE MPI::MPI_CXX INTERFACE_INCLUDE_DIRECTORIES)
set(N2P2_PROJECT_OPTIONS "-I${N2P2_MPI_INCLUDE}")
set(MPI_CXX_COMPILER ${CMAKE_CXX_COMPILER})
endif()
endif()
@ -64,8 +62,8 @@ if(DOWNLOAD_N2P2)
string(TOUPPER "${CMAKE_BUILD_TYPE}" BTYPE)
set(N2P2_BUILD_FLAGS "${CMAKE_SHARED_LIBRARY_CXX_FLAGS} ${CMAKE_CXX_FLAGS} ${CMAKE_CXX_FLAGS_${BTYPE}} ${N2P2_CXX_STD}")
set(N2P2_BUILD_OPTIONS INTERFACES=LAMMPS COMP=${N2P2_COMP} "PROJECT_OPTIONS=${N2P2_PROJECT_OPTIONS}" "PROJECT_DEBUG="
"PROJECT_CC=${CMAKE_CXX_COMPILER}" "PROJECT_MPICC=${MPI_CXX_COMPILER}" "PROJECT_CFLAGS=${N2P2_BUILD_FLAGS}"
"PROJECT_AR=${N2P2_AR}")
"PROJECT_CC=${CMAKE_CXX_COMPILER}" "PROJECT_MPICC=${CMAKE_CXX_COMPILER}" "PROJECT_CFLAGS=${N2P2_BUILD_FLAGS}"
"PROJECT_AR=${N2P2_AR}" "APP_CORE=nnp-convert" "APP_TRAIN=nnp-train" "APP=nnp-convert")
# echo final flag for debugging
message(STATUS "N2P2 BUILD OPTIONS: ${N2P2_BUILD_OPTIONS}")

1
cmake/Modules/Packages/ML-QUIP.cmake
View File

@ -51,6 +51,7 @@ if(DOWNLOAD_QUIP)
GIT_TAG origin/public
GIT_SHALLOW YES
GIT_PROGRESS YES
GIT_SUBMODULES "src/fox;src/GAP"
PATCH_COMMAND ${CMAKE_COMMAND} -E copy_if_different ${CMAKE_BINARY_DIR}/quip.config <SOURCE_DIR>/arch/Makefile.lammps
CONFIGURE_COMMAND env QUIP_ARCH=lammps make config
BUILD_COMMAND env QUIP_ARCH=lammps make libquip

9
cmake/Modules/Packages/PHONON.cmake Normal file
View File

@ -0,0 +1,9 @@
# fix phonon may only be installed if also the FFT wrappers from KSPACE are installed
if(NOT PKG_KSPACE)
get_property(LAMMPS_FIX_HEADERS GLOBAL PROPERTY FIX)
list(REMOVE_ITEM LAMMPS_FIX_HEADERS ${LAMMPS_SOURCE_DIR}/PHONON/fix_phonon.h)
set_property(GLOBAL PROPERTY FIX "${LAMMPS_FIX_HEADERS}")
get_target_property(LAMMPS_SOURCES lammps SOURCES)
list(REMOVE_ITEM LAMMPS_SOURCES ${LAMMPS_SOURCE_DIR}/PHONON/fix_phonon.cpp)
set_property(TARGET lammps PROPERTY SOURCES "${LAMMPS_SOURCES}")
endif()

4
cmake/Modules/Packages/PLUMED.cmake
View File

@ -54,8 +54,8 @@ if(DOWNLOAD_PLUMED)
set(PLUMED_BUILD_BYPRODUCTS "<INSTALL_DIR>/lib/libplumedWrapper.a")
endif()
set(PLUMED_URL "https://github.com/plumed/plumed2/releases/download/v2.7.2/plumed-src-2.7.2.tgz" CACHE STRING "URL for PLUMED tarball")
set(PLUMED_MD5 "cfa0b4dd90a81c25d3302e8d97bfeaea" CACHE STRING "MD5 checksum of PLUMED tarball")
set(PLUMED_URL "https://github.com/plumed/plumed2/releases/download/v2.7.4/plumed-src-2.7.4.tgz" CACHE STRING "URL for PLUMED tarball")
set(PLUMED_MD5 "858e0b6aed173748fc85b6bc8a9dcb3e" CACHE STRING "MD5 checksum of PLUMED tarball")
mark_as_advanced(PLUMED_URL)
mark_as_advanced(PLUMED_MD5)

2
cmake/Modules/Packages/PYTHON.cmake
View File

@ -3,7 +3,7 @@ if(CMAKE_VERSION VERSION_LESS 3.12)
target_include_directories(lammps PRIVATE ${PYTHON_INCLUDE_DIRS})
target_link_libraries(lammps PRIVATE ${PYTHON_LIBRARIES})
else()
find_package(Python REQUIRED COMPONENTS Development)
find_package(Python REQUIRED COMPONENTS Interpreter Development)
target_link_libraries(lammps PRIVATE Python::Python)
endif()
target_compile_definitions(lammps PRIVATE -DLMP_PYTHON)

8
cmake/Modules/generate_lmpgitversion.cmake
View File

@ -24,10 +24,10 @@ if(GIT_FOUND AND EXISTS ${LAMMPS_DIR}/.git)
OUTPUT_STRIP_TRAILING_WHITESPACE)
endif()
set(temp "${temp}const bool LAMMPS_NS::LAMMPS::has_git_info = ${temp_git_info};\n")
set(temp "${temp}const char LAMMPS_NS::LAMMPS::git_commit[] = \"${temp_git_commit}\";\n")
set(temp "${temp}const char LAMMPS_NS::LAMMPS::git_branch[] = \"${temp_git_branch}\";\n")
set(temp "${temp}const char LAMMPS_NS::LAMMPS::git_descriptor[] = \"${temp_git_describe}\";\n")
set(temp "${temp}bool LAMMPS_NS::LAMMPS::has_git_info() { return ${temp_git_info}; }\n")
set(temp "${temp}const char *LAMMPS_NS::LAMMPS::git_commit() { return \"${temp_git_commit}\"; }\n")
set(temp "${temp}const char *LAMMPS_NS::LAMMPS::git_branch() { return \"${temp_git_branch}\"; }\n")
set(temp "${temp}const char *LAMMPS_NS::LAMMPS::git_descriptor() { return \"${temp_git_describe}\"; }\n")
set(temp "${temp}#endif\n\n")
message(STATUS "Generating lmpgitversion.h...")

7
cmake/iwyu/iwyu-extra-map.imp
View File

@ -20,9 +20,14 @@
{ include: [ "@\"kspace_.*.h\"", public, "\"style_kspace.h\"", public ] },
{ include: [ "@\"nbin_.*.h\"", public, "\"style_nbin.h\"", public ] },
{ include: [ "@\"npair_.*.h\"", public, "\"style_npair.h\"", public ] },
{ include: [ "@\"nstenci_.*.h\"", public, "\"style_nstencil.h\"", public ] },
{ include: [ "@\"nstencil_.*.h\"", public, "\"style_nstencil.h\"", public ] },
{ include: [ "@\"ntopo_.*.h\"", public, "\"style_ntopo.h\"", public ] },
{ include: [ "\"fmt/core.h\"", private, "\"fmt/format.h\"", public ] },
{ include: [ "<float.h>", public, "<cfloat>", public ] },
{ include: [ "\"float.h\"", public, "<cfloat>", public ] },
{ include: [ "<limits.h>", public, "<climits>", public ] },
{ include: [ "\"limits.h\"", public, "<climits>", public ] },
{ include: [ "<stdio.h>", public, "<cstdio>", public ] },
{ include: [ "<bits/types/struct_rusage.h>", private, "<sys/types.h>", public ] },
{ include: [ "<bits/types/struct_tm.h>", private, "<ctime>", public ] },
]

6
cmake/presets/gcc.cmake
View File

@ -3,19 +3,19 @@
set(CMAKE_CXX_COMPILER "g++" CACHE STRING "" FORCE)
set(CMAKE_C_COMPILER "gcc" CACHE STRING "" FORCE)
set(CMAKE_Fortran_COMPILER "gfortran" CACHE STRING "" FORCE)
set(CMAKE_CXX_FLAGS_DEBUG "-Wall -g" CACHE STRING "" FORCE)
set(CMAKE_CXX_FLAGS_DEBUG "-Wall -Og -g" CACHE STRING "" FORCE)
set(CMAKE_CXX_FLAGS_RELWITHDEBINFO "-g -O2 -DNDEBUG" CACHE STRING "" FORCE)
set(CMAKE_CXX_FLAGS_RELEASE "-O3 -DNDEBUG" CACHE STRING "" FORCE)
set(MPI_CXX "g++" CACHE STRING "" FORCE)
set(MPI_CXX_COMPILER "mpicxx" CACHE STRING "" FORCE)
set(MPI_C "gcc" CACHE STRING "" FORCE)
set(MPI_C_COMPILER "mpicc" CACHE STRING "" FORCE)
set(CMAKE_C_FLAGS_DEBUG "-Wall -g" CACHE STRING "" FORCE)
set(CMAKE_C_FLAGS_DEBUG "-Wall -Og -g" CACHE STRING "" FORCE)
set(CMAKE_C_FLAGS_RELWITHDEBINFO "-g -O2 -DNDEBUG" CACHE STRING "" FORCE)
set(CMAKE_C_FLAGS_RELEASE "-O3 -DNDEBUG" CACHE STRING "" FORCE)
set(MPI_Fortran "gfortran" CACHE STRING "" FORCE)
set(MPI_Fortran_COMPILER "mpifort" CACHE STRING "" FORCE)
set(CMAKE_Fortran_FLAGS_DEBUG "-Wall -g -std=f2003" CACHE STRING "" FORCE)
set(CMAKE_Fortran_FLAGS_DEBUG "-Wall -Og -g -std=f2003" CACHE STRING "" FORCE)
set(CMAKE_Fortran_FLAGS_RELWITHDEBINFO "-g -O2 -DNDEBUG -std=f2003" CACHE STRING "" FORCE)
set(CMAKE_Fortran_FLAGS_RELEASE "-O3 -DNDEBUG -std=f2003" CACHE STRING "" FORCE)
unset(HAVE_OMP_H_INCLUDE CACHE)

2
doc/lammps.1
View File

@ -1,4 +1,4 @@
.TH LAMMPS "1" "27 October 2021" "2021-10-27"
.TH LAMMPS "1" "17 February 2022" "2022-2-17"
.SH NAME
.B LAMMPS
\- Molecular Dynamics Simulator.

5
doc/src/Bibliography.rst
View File

@ -1123,9 +1123,12 @@ Bibliography
**(Sun)**
Sun, J. Phys. Chem. B, 102, 7338-7364 (1998).
**(Surblys)**
**(Surblys2019)**
Surblys, Matsubara, Kikugawa, Ohara, Phys Rev E, 99, 051301(R) (2019).
**(Surblys2021)**
Surblys, Matsubara, Kikugawa, Ohara, J Appl Phys 130, 215104 (2021).
**(Sutmann)**
Sutmann, Arnold, Fahrenberger, et. al., Physical review / E 88(6), 063308 (2013)

10
doc/src/Build_development.rst
View File

@ -185,6 +185,10 @@ The ``ctest`` command has many options, the most important ones are:
- run subset of tests matching the regular expression <regex>
* - -E <regex>
- exclude subset of tests matching the regular expression <regex>
* - -L <regex>
- run subset of tests with a label matching the regular expression <regex>
* - -LE <regex>
- exclude subset of tests with a label matching the regular expression <regex>
* - -N
- dry-run: display list of tests without running them
* - -T memcheck
@ -299,6 +303,12 @@ will destroy the original file, if the generation run does not complete,
so using *-g* is recommended unless the YAML file is fully tested
and working.
Some of the force style tests are rather slow to run and some are very
sensitive to small differences like CPU architecture, compiler
toolchain, compiler optimization. Those tests are flagged with a "slow"
and/or "unstable" label, and thus those tests can be selectively
excluded with the ``-LE`` flag or selected with the ``-L`` flag.
.. admonition:: Recommendations and notes for YAML files
:class: note

18
doc/src/Build_settings.rst
View File

@ -4,15 +4,15 @@ Optional build settings
LAMMPS can be built with several optional settings. Each sub-section
explain how to do this for building both with CMake and make.
* :ref:`C++11 standard compliance <cxx11>` when building all of LAMMPS
* :ref:`FFT library <fft>` for use with the :doc:`kspace_style pppm <kspace_style>` command
* :ref:`Size of LAMMPS integer types <size>`
* :ref:`Read or write compressed files <gzip>`
* :ref:`Output of JPG and PNG files <graphics>` via the :doc:`dump image <dump_image>` command
* :ref:`Output of movie files <graphics>` via the :doc:`dump_movie <dump_image>` command
* :ref:`Memory allocation alignment <align>`
* :ref:`Workaround for long long integers <longlong>`
* :ref:`Error handling exceptions <exceptions>` when using LAMMPS as a library
* `C++11 standard compliance`_ when building all of LAMMPS
* `FFT library`_ for use with the :doc:`kspace_style pppm <kspace_style>` command
* `Size of LAMMPS integer types and size limits`_
* `Read or write compressed files`_
* `Output of JPG, PNG, and move files` via the :doc:`dump image <dump_image>` or :doc:`dump movie <dump_image>` commands
* `Memory allocation alignment`_
* `Workaround for long long integers`_
* `Exception handling when using LAMMPS as a library`_ to capture errors
* `Trigger selected floating-point exceptions`_
----------

86
doc/src/Build_windows.rst
View File

@ -16,44 +16,52 @@ General remarks
LAMMPS is developed and tested primarily on Linux machines. The vast
majority of HPC clusters and supercomputers today run on Linux as well.
While portability to other platforms is desired, it is not always achieved.
The LAMMPS developers are dependent on LAMMPS users giving feedback and
providing assistance in resolving portability issues. This is particularly
true for compiling LAMMPS on Windows, since this platform has significant
differences in some low-level functionality.
While portability to other platforms is desired, it is not always
achieved. That is sometimes due to non-portable code in LAMMPS itself,
but more often due to portability limitations of external libraries and
tools required to build a specific feature or package. The LAMMPS
developers are dependent on LAMMPS users giving feedback and providing
assistance in resolving portability issues. This is particularly true
for compiling LAMMPS on Windows, since this platform has significant
differences in some low-level functionality. As of LAMMPS version 14
December 2021, large parts of LAMMPS can be compiled natively with the
Microsoft Visual C++ Compilers. This is largely facilitated by using
the :doc:`Developer_platform` in the ``platform`` namespace.
Before trying to build LAMMPS on Windows yourself, please consider the
`pre-compiled Windows installer packages <https://packages.lammps.org/windows.html>`_
and see if they are sufficient for your needs.
.. _linux:
Running Linux on Windows
^^^^^^^^^^^^^^^^^^^^^^^^
Before trying to build LAMMPS on Windows, please consider if the
pre-compiled Windows binary packages are sufficient for your needs. If
it is necessary for you to compile LAMMPS on a Windows machine
If it is necessary for you to compile LAMMPS on a Windows machine
(e.g. because it is your main desktop), please also consider using a
virtual machine software and compile and run LAMMPS in a Linux virtual
machine, or - if you have a sufficiently up-to-date Windows 10 or
Windows 11 installation - consider using the Windows subsystem for
Linux. This optional Windows feature allows you to run the bash shell
from Ubuntu from within Windows and from there on, you can pretty much
use that shell like you are running on an Ubuntu Linux machine
(e.g. installing software via apt-get and more). For more details on
that, please see :doc:`this tutorial <Howto_wsl>`.
of a Linux system (Ubuntu by default) from within Windows and from there
on, you can pretty much use that shell like you are running on a regular
Ubuntu Linux machine (e.g. installing software via apt-get and more).
For more details on that, please see :doc:`this tutorial <Howto_wsl>`.
.. _gnu:
Using a GNU GCC ported to Windows
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
One option for compiling LAMMPS on Windows natively that has been known
to work in the past is to install a bash shell, unix shell utilities,
perl, GNU make, and a GNU compiler ported to Windows. The Cygwin
package provides a unix/linux interface to low-level Windows functions,
so LAMMPS can be compiled on Windows. The necessary (minor)
modifications to LAMMPS are included, but may not always up-to-date for
recently added functionality and the corresponding new code. A machine
makefile for using cygwin for the old build system is provided. Using
CMake for this mode of compilation is untested and not likely to work.
One option for compiling LAMMPS on Windows natively is to install a Bash
shell, Unix shell utilities, Perl, Python, GNU make, and a GNU compiler
ported to Windows. The Cygwin package provides a unix/linux interface
to low-level Windows functions, so LAMMPS can be compiled on Windows.
The necessary (minor) modifications to LAMMPS are included, but may not
always up-to-date for recently added functionality and the corresponding
new code. A machine makefile for using cygwin for the old build system
is provided. Using CMake for this mode of compilation is untested and
not likely to work.
When compiling for Windows do **not** set the ``-DLAMMPS_MEMALIGN``
define in the LMP_INC makefile variable and add ``-lwsock32 -lpsapi`` to
@ -75,19 +83,27 @@ Using Microsoft Visual Studio
Following the integration of the :doc:`platform namespace
<Developer_platform>` into the LAMMPS code base, portability of LAMMPS
to be compiled on Windows using Visual Studio has been significantly
improved. This has been tested with Visual Studio 2019 (aka version
16). Not all features and packages in LAMMPS are currently supported
out of the box, but a preset ``cmake/presets/windows.cmake`` is provided
that contains the packages that have been compiled successfully. You
must use the CMake based build procedure, and either use the integrated
CMake support of Visual Studio or use an external CMake installation to
create build files for the Visual Studio build system. Please note that
on launching Visual Studio it will scan the directory tree and likely
miss the correct master ``CMakeLists.txt``. Try to open the
``cmake/CMakeSettings.json`` and use those CMake configurations as a
starting point. It is also possible to configure and compile LAMMPS
from the command line with a CMake binary from `cmake.org <https://cmake.org>`_.
for native compilation on Windows using Visual Studio has been
significantly improved. This has been tested with Visual Studio 2019
(aka version 16) and Visual Studio 2022 (aka version 17). We strongly
recommend using Visual Studio 2022 version 17.1 or later. Not all
features and packages in LAMMPS are currently supported out of the box,
but a preset ``cmake/presets/windows.cmake`` is provided that contains
the packages that have been compiled successfully so far. You **must**
use the CMake based build procedure, since there is no support for GNU
make or the Unix shell utilities required for the GNU make build
procedure.
It is possible to use both the integrated CMake support of the Visual
Studio IDE or use an external CMake installation (e.g. downloaded from
cmake.org) to create build files and compile LAMMPS from the command line.
.. note::
Versions of Visual Studio before version 17.1 may scan the entire
LAMMPS source tree and likely miss the correct master
``CMakeLists.txt`` and get confused since there are multiple files
of that name in different folders but none in top level folder.
Please note, that for either approach CMake will create a so-called
:ref:`"multi-configuration" build environment <cmake_multiconfig>`, and
@ -98,6 +114,8 @@ To support running in parallel you can compile with OpenMP enabled using
the OPENMP package or install Microsoft MPI (including the SDK) and compile
LAMMPS with MPI enabled.
.. note::
This is work in progress and you should contact the LAMMPS developers
via GitHub, the forum, or the mailing list, if you have questions or
LAMMPS specific problems.

4
doc/src/Commands_all.rst
View File

@ -47,7 +47,7 @@ An alphabetic list of all general LAMMPS commands.
* :doc:`displace_atoms <displace_atoms>`
* :doc:`dump <dump>`
* :doc:`dump_modify <dump_modify>`
* :doc:`dynamical_matrix <dynamical_matrix>`
* :doc:`dynamical_matrix (k) <dynamical_matrix>`
* :doc:`echo <echo>`
* :doc:`fix <fix>`
* :doc:`fix_modify <fix_modify>`
@ -118,7 +118,7 @@ An alphabetic list of all general LAMMPS commands.
* :doc:`thermo <thermo>`
* :doc:`thermo_modify <thermo_modify>`
* :doc:`thermo_style <thermo_style>`
* :doc:`third_order <third_order>`
* :doc:`third_order (k) <third_order>`
* :doc:`timer <timer>`
* :doc:`timestep <timestep>`
* :doc:`uncompute <uncompute>`

1
doc/src/Commands_bond.rst
View File

@ -35,6 +35,7 @@ OPT.
* :doc:`class2 (ko) <bond_class2>`
* :doc:`fene (iko) <bond_fene>`
* :doc:`fene/expand (o) <bond_fene_expand>`
* :doc:`fene/nm <bond_fene>`
* :doc:`gaussian <bond_gaussian>`
* :doc:`gromos (o) <bond_gromos>`
* :doc:`harmonic (iko) <bond_harmonic>`

5
doc/src/Commands_compute.rst
View File

@ -28,6 +28,7 @@ KOKKOS, o = OPENMP, t = OPT.
* :doc:`angle <compute_angle>`
* :doc:`angle/local <compute_angle_local>`
* :doc:`angmom/chunk <compute_angmom_chunk>`
* :doc:`ave/sphere/atom (k) <compute_ave_sphere_atom>`
* :doc:`basal/atom <compute_basal_atom>`
* :doc:`body/local <compute_body_local>`
* :doc:`bond <compute_bond>`
@ -99,7 +100,6 @@ KOKKOS, o = OPENMP, t = OPT.
* :doc:`pe/tally <compute_tally>`
* :doc:`plasticity/atom <compute_plasticity_atom>`
* :doc:`pressure <compute_pressure>`
* :doc:`pressure/cylinder <compute_pressure_cylinder>`
* :doc:`pressure/uef <compute_pressure_uef>`
* :doc:`property/atom <compute_property_atom>`
* :doc:`property/chunk <compute_property_chunk>`
@ -142,8 +142,11 @@ KOKKOS, o = OPENMP, t = OPT.
* :doc:`sph/t/atom <compute_sph_t_atom>`
* :doc:`spin <compute_spin>`
* :doc:`stress/atom <compute_stress_atom>`
* :doc:`stress/cartesian <compute_stress_profile>`
* :doc:`stress/cylinder <compute_stress_profile>`
* :doc:`stress/mop <compute_stress_mop>`
* :doc:`stress/mop/profile <compute_stress_mop>`
* :doc:`stress/spherical <compute_stress_profile>`
* :doc:`stress/tally <compute_tally>`
* :doc:`tdpd/cc/atom <compute_tdpd_cc_atom>`
* :doc:`temp (k) <compute_temp>`

3
doc/src/Commands_fix.rst
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@ -97,8 +97,6 @@ OPT.
* :doc:`latte <fix_latte>`
* :doc:`lb/fluid <fix_lb_fluid>`
* :doc:`lb/momentum <fix_lb_momentum>`
* :doc:`lb/pc <fix_lb_pc>`
* :doc:`lb/rigid/pc/sphere <fix_lb_rigid_pc_sphere>`
* :doc:`lb/viscous <fix_lb_viscous>`
* :doc:`lineforce <fix_lineforce>`
* :doc:`manifoldforce <fix_manifoldforce>`
@ -129,6 +127,7 @@ OPT.
* :doc:`npt/sphere (o) <fix_npt_sphere>`
* :doc:`npt/uef <fix_nh_uef>`
* :doc:`numdiff <fix_numdiff>`
* :doc:`numdiff/virial <fix_numdiff_virial>`
* :doc:`nve (giko) <fix_nve>`
* :doc:`nve/asphere (gi) <fix_nve_asphere>`
* :doc:`nve/asphere/noforce <fix_nve_asphere_noforce>`

5
doc/src/Commands_pair.rst
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@ -119,10 +119,12 @@ OPT.
* :doc:`granular <pair_granular>`
* :doc:`gw <pair_gw>`
* :doc:`gw/zbl <pair_gw>`
* :doc:`harmonic/cut (o) <pair_harmonic_cut>`
* :doc:`hbond/dreiding/lj (o) <pair_hbond_dreiding>`
* :doc:`hbond/dreiding/morse (o) <pair_hbond_dreiding>`
* :doc:`hdnnp <pair_hdnnp>`
* :doc:`ilp/graphene/hbn <pair_ilp_graphene_hbn>`
* :doc:`ilp/tmd <pair_ilp_tmd>`
* :doc:`kolmogorov/crespi/full <pair_kolmogorov_crespi_full>`
* :doc:`kolmogorov/crespi/z <pair_kolmogorov_crespi_z>`
* :doc:`lcbop <pair_lcbop>`
@ -210,6 +212,7 @@ OPT.
* :doc:`nm/cut (o) <pair_nm>`
* :doc:`nm/cut/coul/cut (o) <pair_nm>`
* :doc:`nm/cut/coul/long (o) <pair_nm>`
* :doc:`nm/cut/split <pair_nm>`
* :doc:`oxdna/coaxstk <pair_oxdna>`
* :doc:`oxdna/excv <pair_oxdna>`
* :doc:`oxdna/hbond <pair_oxdna>`
@ -239,6 +242,7 @@ OPT.
* :doc:`reaxff (ko) <pair_reaxff>`
* :doc:`rebo (io) <pair_airebo>`
* :doc:`resquared (go) <pair_resquared>`
* :doc:`saip/metal <pair_saip_metal>`
* :doc:`sdpd/taitwater/isothermal <pair_sdpd_taitwater_isothermal>`
* :doc:`smd/hertz <pair_smd_hertz>`
* :doc:`smd/tlsph <pair_smd_tlsph>`
@ -262,6 +266,7 @@ OPT.
* :doc:`spin/neel <pair_spin_neel>`
* :doc:`srp <pair_srp>`
* :doc:`sw (giko) <pair_sw>`
* :doc:`sw/mod (o) <pair_sw>`
* :doc:`table (gko) <pair_table>`
* :doc:`table/rx (k) <pair_table_rx>`
* :doc:`tdpd <pair_mesodpd>`

2
doc/src/Developer.rst
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@ -11,7 +11,9 @@ of time and requests from the LAMMPS user community.
:maxdepth: 1
Developer_org
Developer_code_design
Developer_parallel
Developer_comm_ops
Developer_flow
Developer_write
Developer_notes

433
doc/src/Developer_code_design.rst Normal file
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@ -0,0 +1,433 @@
Code design
-----------
This section explains some of the code design choices in LAMMPS with
the goal of helping developers write new code similar to the existing
code. Please see the section on :doc:`Requirements for contributed
code <Modify_style>` for more specific recommendations and guidelines.
While that section is organized more in the form of a checklist for
code contributors, the focus here is on overall code design strategy,
choices made between possible alternatives, and discussing some
relevant C++ programming language constructs.
Historically, the basic design philosophy of the LAMMPS C++ code was a
"C with classes" style. The motivation was to make it easy to modify
LAMMPS for people without significant training in C++ programming.
Data structures and code constructs were used that resemble the
previous implementation(s) in Fortran. A contributing factor to this
choice also was that at the time, C++ compilers were often not mature
and some of the advanced features contained bugs or did not function
as the standard required. There were also disagreements between
compiler vendors as to how to interpret the C++ standard documents.
However, C++ compilers have now advanced significantly. In 2020 we
decided to to require the C++11 standard as the minimum C++ language
standard for LAMMPS. Since then we have begun to also replace some of
the C-style constructs with equivalent C++ functionality, either from
the C++ standard library or as custom classes or functions, in order
to improve readability of the code and to increase code reuse through
abstraction of commonly used functionality.
.. note::
Please note that as of spring 2022 there is still a sizable chunk
of legacy code in LAMMPS that has not yet been refactored to
reflect these style conventions in full. LAMMPS has a large code
base and many different contributors and there also is a hierarchy
of precedence in which the code is adapted. Highest priority has
been the code in the ``src`` folder, followed by code in packages
in order of their popularity and complexity (simpler code is
adapted sooner), followed by code in the ``lib`` folder. Source
code that is downloaded from external packages or libraries during
compilation is not subject to the conventions discussed here.
Object oriented code
^^^^^^^^^^^^^^^^^^^^
LAMMPS is designed to be an object oriented code. Each simulation is
represented by an instance of the LAMMPS class. When running in
parallel each MPI process creates such an instance. This can be seen
in the ``main.cpp`` file where the core steps of running a LAMMPS
simulation are the following 3 lines of code:
.. code-block:: C++
LAMMPS *lammps = new LAMMPS(argc, argv, lammps_comm);
lammps->input->file();
delete lammps;
The first line creates a LAMMPS class instance and passes the command
line arguments and the global communicator to its constructor. The
second line triggers the LAMMPS instance to process the input (either
from standard input or a provided input file) until the simulation
ends. The third line deletes the LAMMPS instance. The remainder of
the main.cpp file has code for error handling, MPI configuration, and
other special features.
The basic LAMMPS class hierarchy which is created by the LAMMPS class
constructor is shown in :ref:`class-topology`. When input commands
are processed, additional class instances are created, or deleted, or
replaced. Likewise specific member functions of specific classes are
called to trigger actions such creating atoms, computing forces,
computing properties, time-propagating the system, or writing output.
Compositing and Inheritance
===========================
LAMMPS makes extensive use of the object oriented programming (OOP)
principles of *compositing* and *inheritance*. Classes like the
``LAMMPS`` class are a **composite** containing pointers to instances
of other classes like ``Atom``, ``Comm``, ``Force``, ``Neighbor``,
``Modify``, and so on. Each of these classes implement certain
functionality by storing and manipulating data related to the
simulation and providing member functions that trigger certain
actions. Some of those classes like ``Force`` are themselves
composites, containing instances of classes describing different force
interactions. Similarly the ``Modify`` class contains a list of
``Fix`` and ``Compute`` classes. If the input commands that
correspond to these classes include the word *style*, then LAMMPS
stores only a single instance of that class. E.g. *atom_style*,
*comm_style*, *pair_style*, *bond_style*. It the input command does
not include the word *style*, there can be many instances of that
class defined. E.g. *region*, *fix*, *compute*, *dump*.
**Inheritance** enables creation of *derived* classes that can share
common functionality in their base class while providing a consistent
interface. The derived classes replace (dummy or pure) functions in
the base class. The higher level classes can then call those methods
of the instantiated classes without having to know which specific
derived class variant was instantiated. In LAMMPS these derived
classes are often referred to as "styles", e.g. pair styles, fix
styles, atom styles and so on.
This is the origin of the flexibility of LAMMPS. For example pair
styles implement a variety of different non-bonded interatomic
potentials functions. All details for the implementation of a
potential are stored and executed in a single class.
As mentioned above, there can be multiple instances of classes derived
from the ``Fix`` or ``Compute`` base classes. They represent a
different facet of LAMMPS flexibility as they provide methods which
can be called at different points in time within a timestep, as
explained in `Developer_flow`. This allows the input script to tailor
how a specific simulation is run, what diagnostic computations are
performed, and how the output of those computations is further
processed or output.
Additional code sharing is possible by creating derived classes from the
derived classes (e.g., to implement an accelerated version of a pair
style) where only a subset of the derived class methods are replaced
with accelerated versions.
Polymorphism
============
Polymorphism and dynamic dispatch are another OOP feature that play an
important role in how LAMMPS selects what code to execute. In a
nutshell, this is a mechanism where the decision of which member
function to call from a class is determined at runtime and not when
the code is compiled. To enable it, the function has to be declared
as ``virtual`` and all corresponding functions in derived classes
should use the ``override`` property. Below is a brief example.
.. code-block:: c++
class Base {
public:
virtual ~Base() = default;
void call();
void normal();
virtual void poly();
};
void Base::call() {
normal();
poly();
}
class Derived : public Base {
public:
~Derived() override = default;
void normal();
void poly() override;
};
// [....]
Base *base1 = new Base();
Base *base2 = new Derived();
base1->call();
base2->call();
The difference in behavior of the ``normal()`` and the ``poly()`` member
functions is which of the two member functions is called when executing
`base1->call()` versus `base2->call()`. Without polymorphism, a
function within the base class can only call member functions within the
same scope, that is ``Base::call()`` will always call
``Base::normal()``. But for the `base2->call()` case the call of the
virtual member function will be dispatched to ``Derived::poly()``
instead. This mechanism means that functions are called within the
scope of the class type that was used to *create* the class instance are
invoked; even if they are assigned to a pointer using the type of a base
class. This is the desired behavior and this way LAMMPS can even use
styles that are loaded at runtime from a shared object file with the
:doc:`plugin command <plugin>`.
A special case of virtual functions are so-called pure functions. These
are virtual functions that are initialized to 0 in the class declaration
(see example below).
.. code-block:: c++
class Base {
public:
virtual void pure() = 0;
};
This has the effect that an instance of the base class cannot be
created and that derived classes **must** implement these functions.
Many of the functions listed with the various class styles in the
section :doc:`Modify` are pure functions. The motivation for this is
to define the interface or API of the functions but defer their
implementation to the derived classes.
However, there are downsides to this. For example, calls to virtual
functions from within a constructor, will not be in the scope of the
derived class and thus it is good practice to either avoid calling them
or to provide an explicit scope such as ``Base::poly()`` or
``Derived::poly()``. Furthermore, any destructors in classes containing
virtual functions should be declared virtual too, so they will be
processed in the expected order before types are removed from dynamic
dispatch.
.. admonition:: Important Notes
In order to be able to detect incompatibilities at compile time and
to avoid unexpected behavior, it is crucial that all member functions
that are intended to replace a virtual or pure function use the
``override`` property keyword. For the same reason, the use of
overloads or default arguments for virtual functions should be
avoided as they lead to confusion over which function is supposed to
override which and which arguments need to be declared.
Style Factories
===============
In order to create class instances for different styles, LAMMPS often
uses a programming pattern called `Factory`. Those are functions that
create an instance of a specific derived class, say ``PairLJCut`` and
return a pointer to the type of the common base class of that style,
``Pair`` in this case. To associate the factory function with the
style keyword, an ``std::map`` class is used with function pointers
indexed by their keyword (for example "lj/cut" for ``PairLJCut`` and
"morse" for ``PairMorse``). A couple of typedefs help keep the code
readable and a template function is used to implement the actual
factory functions for the individual classes. Below is an example
of such a factory function from the ``Force`` class as declared in
``force.h`` and implemented in ``force.cpp``. The file ``style_pair.h``
is generated during compilation and includes all main header files
(i.e. those starting with ``pair_``) of pair styles and then the
macro ``PairStyle()`` will associate the style name "lj/cut"
with a factory function creating an instance of the ``PairLJCut``
class.
.. code-block:: C++
// from force.h
typedef Pair *(*PairCreator)(LAMMPS *);
typedef std::map<std::string, PairCreator> PairCreatorMap;
PairCreatorMap *pair_map;
// from force.cpp
template <typename S, typename T> static S *style_creator(LAMMPS *lmp)
{
return new T(lmp);
}
// [...]
pair_map = new PairCreatorMap();
#define PAIR_CLASS
#define PairStyle(key, Class) (*pair_map)[#key] = &style_creator<Pair, Class>;
#include "style_pair.h"
#undef PairStyle
#undef PAIR_CLASS
// from pair_lj_cut.h
#ifdef PAIR_CLASS
PairStyle(lj/cut,PairLJCut);
#else
// [...]
Similar code constructs are present in other files like ``modify.cpp`` and
``modify.h`` or ``neighbor.cpp`` and ``neighbor.h``. Those contain
similar macros and include ``style_*.h`` files for creating class instances
of styles they manage.
I/O and output formatting
^^^^^^^^^^^^^^^^^^^^^^^^^
C-style stdio versus C++ style iostreams
========================================
LAMMPS uses the "stdio" library of the standard C library for reading
from and writing to files and console instead of C++ "iostreams".
This is mainly motivated by better performance, better control over
formatting, and less effort to achieve specific formatting.
Since mixing "stdio" and "iostreams" can lead to unexpected
behavior. use of the latter is strongly discouraged. Also output to
the screen should not use the predefined ``stdout`` FILE pointer, but
rather the ``screen`` and ``logfile`` FILE pointers managed by the
LAMMPS class. Furthermore, output should generally only be done by
MPI rank 0 (``comm->me == 0``). Output that is sent to both
``screen`` and ``logfile`` should use the :cpp:func:`utils::logmesg()
convenience function <LAMMPS_NS::utils::logmesg>`.
We also discourage the use of stringstreams because the bundled {fmt}
library and the customized tokenizer classes can provide the same
functionality in a cleaner way with better performance. This also
helps maintain a consistent programming syntax with code from many
different contributors.
Formatting with the {fmt} library
===================================
The LAMMPS source code includes a copy of the `{fmt} library
<https://fmt.dev>`_ which is preferred over formatting with the
"printf()" family of functions. The primary reason is that it allows
a typesafe default format for any type of supported data. This is
particularly useful for formatting integers of a given size (32-bit or
64-bit) which may require different format strings depending on
compile time settings or compilers/operating systems. Furthermore,
{fmt} gives better performance, has more functionality, a familiar
formatting syntax that has similarities to ``format()`` in Python, and
provides a facility that can be used to integrate format strings and a
variable number of arguments into custom functions in a much simpler
way than the varargs mechanism of the C library. Finally, {fmt} has
been included into the C++20 language standard, so changes to adopt it
are future-proof.
Formatted strings are frequently created by calling the
``fmt::format()`` function which will return a string as a
``std::string`` class instance. In contrast to the ``%`` placeholder
in ``printf()``, the {fmt} library uses ``{}`` to embed format
descriptors. In the simplest case, no additional characters are
needed as {fmt} will choose the default format based on the data type
of the argument. Otherwise the ``fmt::print()`` function may be
used instead of ``printf()`` or ``fprintf()``. In addition, several
LAMMPS output functions, that originally accepted a single string as
argument have been overloaded to accept a format string with optional
arguments as well (e.g., ``Error::all()``, ``Error::one()``,
``utils::logmesg()``).
Summary of the {fmt} format syntax
==================================
The syntax of the format string is "{[<argument id>][:<format spec>]}",
where either the argument id or the format spec (separated by a colon
':') is optional. The argument id is usually a number starting from 0
that is the index to the arguments following the format string. By
default these are assigned in order (i.e. 0, 1, 2, 3, 4 etc.). The most
common case for using argument id would be to use the same argument in
multiple places in the format string without having to provide it as an
argument multiple times. In LAMMPS the argument id is rarely used.
More common is the use of a format specifier, which starts with a colon.
This may optionally be followed by a fill character (default is ' '). If
provided, the fill character **must** be followed by an alignment
character ('<', '^', '>' for left, centered, or right alignment
(default)). The alignment character may be used without a fill
character. The next important format parameter would be the minimum
width, which may be followed by a dot '.' and a precision for floating
point numbers. The final character in the format string would be an
indicator for the "presentation", i.e. 'd' for decimal presentation of
integers, 'x' for hexadecimal, 'o' for octal, 'c' for character etc.
This mostly follows the "printf()" scheme but without requiring an
additional length parameter to distinguish between different integer
widths. The {fmt} library will detect those and adapt the formatting
accordingly. For floating point numbers there are correspondingly, 'g'
for generic presentation, 'e' for exponential presentation, and 'f' for
fixed point presentation.
Thus "{:8}" would represent *any* type argument using at least 8
characters; "{:<8}" would do this as left aligned, "{:^8}" as centered,
"{:>8}" as right aligned. If a specific presentation is selected, the
argument type must be compatible or else the {fmt} formatting code will
throw an exception. Some format string examples are given below:
.. code-block:: C
auto mesg = fmt::format(" CPU time: {:4d}:{:02d}:{:02d}\n", cpuh, cpum, cpus);
mesg = fmt::format("{:<8s}| {:<10.5g} | {:<10.5g} | {:<10.5g} |{:6.1f} |{:6.2f}\n",
label, time_min, time, time_max, time_sq, tmp);
utils::logmesg(lmp,"{:>6} = max # of 1-2 neighbors\n",maxall);
utils::logmesg(lmp,"Lattice spacing in x,y,z = {:.8} {:.8} {:.8}\n",
xlattice,ylattice,zlattice);
which will create the following output lines:
.. parsed-literal::
CPU time: 0:02:16
Pair | 2.0133 | 2.0133 | 2.0133 | 0.0 | 84.21
4 = max # of 1-2 neighbors
Lattice spacing in x,y,z = 1.6795962 1.6795962 1.6795962
Finally, a special feature of the {fmt} library is that format
parameters like the width or the precision may be also provided as
arguments. In that case a nested format is used where a pair of curly
braces (with an optional argument id) "{}" are used instead of the
value, for example "{:{}d}" will consume two integer arguments, the
first will be the value shown and the second the minimum width.
For more details and examples, please consult the `{fmt} syntax
documentation <https://fmt.dev/latest/syntax.html>`_ website.
Memory management
^^^^^^^^^^^^^^^^^
Dynamical allocation of small data and objects can be done with the
the C++ commands "new" and "delete/delete[]. Large data should use
the member functions of the ``Memory`` class, most commonly,
``Memory::create()``, ``Memory::grow()``, and ``Memory::destroy()``,
which provide variants for vectors, 2d arrays, 3d arrays, etc.
These can also be used for small data.
The use of ``malloc()``, ``calloc()``, ``realloc()`` and ``free()``
directly is strongly discouraged. To simplify adapting legacy code
into the LAMMPS code base the member functions ``Memory::smalloc()``,
``Memory::srealloc()``, and ``Memory::sfree()`` are available, which
perform additional error checks for safety.
Use of these custom memory allocation functions is motivated by the
following considerations:
- memory allocation failures on *any* MPI rank during a parallel run
will trigger an immediate abort of the entire parallel calculation
instead of stalling it
- a failing "new" will trigger an exception which is also captured by
LAMMPS and triggers a global abort
- allocation of multi-dimensional arrays will be done in a C compatible
fashion but so that the storage of the actual data is stored in one
large contiguous block. Thus when MPI communication is needed,
the data can be communicated directly (similar to Fortran arrays).
- the "destroy()" and "sfree()" functions may safely be called on NULL
pointers
- the "destroy()" functions will nullify the pointer variables making
"use after free" errors easy to detect
- it is possible to use a larger than default memory alignment (not on
all operating systems, since the allocated storage pointers must be
compatible with ``free()`` for technical reasons)
In the practical implementation of code this means that any pointer
variables that are class members should be initialized to a
``nullptr`` value in their respective constructors. That way it is
safe to call ``Memory::destroy()`` or ``delete[]`` on them before
*any* allocation outside the constructor. This helps prevent memory
leaks.

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Communication patterns
----------------------
This page describes various inter-processor communication operations
provided by LAMMPS, mostly in the core *Comm* class. These are operations
for common tasks implemented using MPI library calls. They are used by
other classes to perform communication of different kinds. These
operations are useful to know about when writing new code for LAMMPS
that needs to communicate data between processors.
Owned and ghost atoms
^^^^^^^^^^^^^^^^^^^^^
As described on the :doc:`parallel partitioning algorithms
<Developer_par_part>` page, LAMMPS spatially decomposes the simulation
domain, either in a *brick* or *tiled* manner. Each processor (MPI
task) owns atoms within its sub-domain and additionally stores ghost
atoms within a cutoff distance of its sub-domain.
Forward and reverse communication
=================================
As described on the :doc:`parallel communication algorithms
<Developer_par_comm>` page, the most common communication operations are
first, *forward communication* which sends owned atom information from
each processor to nearby processors to store with their ghost atoms.
The need to do this communication arises when data from the owned atoms
is updated (e.g. their positions) and this updated information needs to
be **copied** to the corresponding ghost atoms.
And second, *reverse communication* which sends ghost atom information
from each processor to the owning processor to **accumulate** (sum)
the values with the corresponding owned atoms. The need for this
arises when data is computed and also stored with ghost atoms
(e.g. forces when using a "half" neighbor list) and thus those terms
need to be added to their corresponding atoms on the process where
they are "owned" atoms. Please note, that with the :doc:`newton off
<newton>` setting this does not happen and the neighbor lists are
constructed so that these interactions are computed on both MPI
processes containing one of the atoms and only the data pertaining to
the local atom is stored.
The time-integration classes in LAMMPS invoke these operations each
timestep via the *forward_comm()* and *reverse_comm()* methods in the
*Comm* class. Which per-atom data is communicated depends on the
currently used :doc:`atom style <atom_style>` and whether
:doc:`comm_modify vel <comm_modify>` setting is "no" (default) or
"yes".
Similarly, *Pair* style classes can invoke the *forward_comm(this)*
and *reverse_comm(this)* methods in the *Comm* class to perform the
same operations on per-atom data that is generated and stored within
the pair style class. Note that this function requires passing the
``this`` pointer as the first argument to enable the *Comm* class to
call the "pack" and "unpack" functions discussed below. An example of
the use of these functions are many-body pair styles like the
embedded-atom method (EAM) which compute intermediate values in the
first part of the compute() function that need to be stored by both
owned and ghost atoms for the second part of the force computation.
The *Comm* class methods perform the MPI communication for buffers of
per-atom data. They "call back" to the *Pair* class so it can *pack*
or *unpack* the buffer with data the *Pair* class owns. There are 4
such methods that the *Pair* class must define, assuming it uses both
forward and reverse communication:
* pack_forward_comm()
* unpack_forward_comm()
* pack_reverse_comm()
* unpack_reverse_comm()
The arguments to these methods include the buffer and a list of atoms
to pack or unpack. The *Pair* class also must set the *comm_forward*
and *comm_reverse* variables which store the number of values stored
in the communication buffers for each operation. This means, if
desired, it can choose to store multiple per-atom values in the
buffer, and they will be communicated together to minimize
communication overhead. The communication buffers are defined vectors
containing ``double`` values. To correctly store integers that may be
64-bit (bigint, tagint, imageint) in the buffer, you need to use the
`ubuf union <Communication buffer coding with ubuf>`_ construct.
The *Fix*, *Compute*, and *Dump* classes can also invoke the same kind
of forward and reverse communication operations using the same *Comm*
class methods. Likewise the same pack/unpack methods and
comm_forward/comm_reverse variables must be defined by the calling
*Fix*, *Compute*, or *Dump* class.
For *Fix* classes there is an optional second argument to the
*forward_comm()* and *reverse_comm()* call which can be used when the
fix performs multiple modes of communication, with different numbers
of values per atom. The fix should set the *comm_forward* and
*comm_reverse* variables to the maximum value, but can invoke the
communication for a particular mode with a smaller value. For this
to work, the *pack_forward_comm()*, etc methods typically use a class
member variable to choose which values to pack/unpack into/from the
buffer.
Finally, for reverse communications in *Fix* classes there is also the
*reverse_comm_variable()* method that allows the communication to have
a different amount of data per-atom. It invokes these corresponding
callback methods:
* pack_reverse_comm_size()
* unpack_reverse_comm_size()
which have extra arguments to specify the amount of data stored
in the buffer for each atom.
Higher level communication
^^^^^^^^^^^^^^^^^^^^^^^^^^
There are also several higher-level communication operations provided
in LAMMPS which work for either *brick* or *tiled* decompositions.
They may be useful for a new class to invoke if it requires more
sophisticated communication than the *forward* and *reverse* methods
provide. The 3 communication operations described here are
* ring
* irregular
* rendezvous
You can invoke these *grep* command in the LAMMPS src directory, to
see a list of classes that invoke the 3 operations.
* ``grep "\->ring" *.cpp */*.cpp``
* ``grep "irregular\->" *.cpp``
* ``grep "\->rendezvous" *.cpp */*.cpp``
Ring operation
==============
The *ring* operation is invoked via the *ring()* method in the *Comm*
class.
Each processor first creates a buffer with a list of values, typically
associated with a subset of the atoms it owns. Now think of the *P*
processors as connected to each other in a *ring*. Each processor *M*
sends data to the next *M+1* processor. It receives data from the
preceding *M-1* processor. The ring is periodic so that the last
processor sends to the first processor, and the first processor
receives from the last processor.
Invoking the *ring()* method passes each processor's buffer in *P*
steps around the ring. At each step a *callback* method, provided as
an argument to ring(), in the caller is invoked. This allows each
processor to examine the data buffer provided by every other
processor. It may extract values needed by its atoms from the
buffers, or it may alter placeholder values in the buffer. In the
latter case, when the *ring* operation is complete, each processor can
examine its original buffer to extract modified values.
Note that the *ring* operation is similar to an MPI_Alltoall()
operation where every processor effectively sends and receives data to
every other processor. The difference is that the *ring* operation
does it one step at a time, so the total volume of data does not need
to be stored by every processor. However, the *ring* operation is
also less efficient than MPI_Alltoall() because of the *P* stages
required. So it is typically only suitable for small data buffers and
occasional operations that are not time-critical.
Irregular operation
===================
The *irregular* operation is provided by the *Irregular* class. What
LAMMPS terms irregular communication is when each processor knows what
data it needs to send to what processor, but does not know what
processors are sending it data. An example is when load-balancing is
performed and each processor needs to send some of its atoms to new
processors.
The *Irregular* class provides 5 high-level methods useful in this
context:
* create_data()
* exchange_data()
* create_atom()
* exchange_atom()
* migrate_atoms()
For the *create_data()* method, each processor specifies a list of *N*
datums to send, each to a specified processor. Internally, the method
creates efficient data structures for performing the communication.
The *exchange_data()* method triggers the communication to be
performed. Each processor provides the vector of *N* datums to send,
and the size of each datum. All datums must be the same size.
The *create_atom()* and *exchange_atom()* methods are similar except
that the size of each datum can be different. Typically this is used
to communicate atoms, each with a variable amount of per-atom data, to
other processors.
The *migrate_atoms()* method is a convenience wrapper on the
*create_atom()* and *exchange_atom()* methods to simplify
communication of all the per-atom data associated with an atom so that
the atom can effectively migrate to a new owning processor. It is
similar to the *exchange()* method in the *Comm* class invoked when
atoms move to neighboring processors (in the regular or tiled
decomposition) during timestepping, except that it allows atoms to
have moved arbitrarily long distances and still be properly
communicated to a new owning processor.
Rendezvous operation
====================
Finally, the *rendezvous* operation is invoked via the *rendezvous()*
method in the *Comm* class. Depending on how much communication is
needed and how many processors a LAMMPS simulation is running on, it
can be a much more efficient choice than the *ring()* method. It uses
the *irregular* operation internally once or twice to do its
communication. The rendezvous algorithm is described in detail in
:ref:`(Plimpton) <Plimpton>`, including some LAMMPS use cases.
For the *rendezvous()* method, each processor specifies a list of *N*
datums to send and which processor to send each of them to.
Internally, this communication is performed as an irregular operation.
The received datums are returned to the caller via invocation of
*callback* function, provided as an argument to *rendezvous()*. The
caller can then process the received datums and (optionally) assemble
a new list of datums to communicate to a new list of specific
processors. When the callback function exits, the *rendezvous()*
method performs a second irregular communication on the new list of
datums.
Examples in LAMMPS of use of the *rendezvous* operation are the
:doc:`fix rigid/small <fix_rigid>` and :doc:`fix shake
<fix_shake>` commands (for one-time identification of the rigid body
atom clusters) and the identification of special_bond 1-2, 1-3 and 1-4
neighbors within molecules. See the :doc:`special_bonds <special_bonds>`
command for context.
----------
.. _Plimpton:
**(Plimpton)** Plimpton and Knight, JPDC, 147, 184-195 (2021).

209
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@ -7,6 +7,215 @@ typically document what a variable stores, what a small section of
code does, or what a function does and its input/outputs. The topics
on this page are intended to document code functionality at a higher level.
Available topics are:
- `Reading and parsing of text and text files`_
- `Requesting and accessing neighbor lists`_
- `Fix contributions to instantaneous energy, virial, and cumulative energy`_
- `KSpace PPPM FFT grids`_
----
Reading and parsing of text and text files
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
It is frequently required for a class in LAMMPS to read in additional
data from a file, e.g. potential parameters from a potential file for
manybody potentials. LAMMPS provides several custom classes and
convenience functions to simplify the process. They offer the
following benefits:
- better code reuse and fewer lines of code needed to implement reading
and parsing data from a file
- better detection of format errors, incompatible data, and better error messages
- exit with an error message instead of silently converting only part of the
text to a number or returning a 0 on unrecognized text and thus reading incorrect values
- re-entrant code through avoiding global static variables (as used by ``strtok()``)
- transparent support for translating unsupported UTF-8 characters to their ASCII equivalents
(the text-to-value conversion functions **only** accept ASCII characters)
In most cases (e.g. potential files) the same data is needed on all MPI
ranks. Then it is best to do the reading and parsing only on MPI rank
0, and communicate the data later with one or more ``MPI_Bcast()``
calls. For reading generic text and potential parameter files the
custom classes :cpp:class:`TextFileReader <LAMMPS_NS::TextFileReader>`
and :cpp:class:`PotentialFileReader <LAMMPS_NS::PotentialFileReader>`
are available. They allow reading the file as individual lines for which
they can return a tokenizer class (see below) for parsing the line. Or
they can return blocks of numbers as a vector directly. The
documentation on :ref:`File reader classes <file-reader-classes>`
contains an example for a typical case.
When reading per-atom data, the data on each line of the file usually
needs to include an atom ID so it can be associated with a particular
atom. In that case the data can be read in multi-line chunks and
broadcast to all MPI ranks with
:cpp:func:`utils::read_lines_from_file()
<LAMMPS_NS::utils::read_lines_from_file>`. Those chunks are then
split into lines, parsed, and applied only to atoms the MPI rank
"owns".
For splitting a string (incrementally) into words and optionally
converting those to numbers, the :cpp:class:`Tokenizer
<LAMMPS_NS::Tokenizer>` and :cpp:class:`ValueTokenizer
<LAMMPS_NS::ValueTokenizer>` can be used. Those provide a superset of
the functionality of ``strtok()`` from the C-library and the latter
also includes conversion to different types. Any errors while
processing the string in those classes will result in an exception,
which can be caught and the error processed as needed. Unlike the
C-library functions ``atoi()``, ``atof()``, ``strtol()``, or
``strtod()`` the conversion will check if the converted text is a
valid integer or floating point number and will not silently return an
unexpected or incorrect value. For example, ``atoi()`` will return 12
when converting "12.5", while the ValueTokenizer class will throw an
:cpp:class:`InvalidIntegerException
<LAMMPS_NS::InvalidIntegerException>` if
:cpp:func:`ValueTokenizer::next_int()
<LAMMPS_NS::ValueTokenizer::next_int>` is called on the same string.
Requesting and accessing neighbor lists
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
LAMMPS uses Verlet-style neighbor lists to avoid having to loop over
*all* pairs of *all* atoms when computing pairwise properties with a
cutoff (e.g. pairwise forces or radial distribution functions). There
are three main algorithms that can be selected by the :doc:`neighbor
command <neighbor>`: `bin` (the default, uses binning to achieve linear
scaling with system size), `nsq` (without binning, quadratic scaling),
`multi` (with binning, optimized for varying cutoffs or polydisperse
granular particles). In addition to how the neighbor lists are
constructed a number of different variants of neighbor lists need to be
created (e.g. "full" or "half") for different purposes and styles and
those may be required in every time step ("perpetual") or on some steps
("occasional").
The neighbor list creation is managed by the ``Neighbor`` class.
Individual classes can obtain a neighbor list by creating an instance of
a ``NeighRequest`` class which is stored in a list inside the
``Neighbor`` class. The ``Neighbor`` class will then analyze the
various requests and apply optimizations where neighbor lists that have
the same settings will be created only once and then copied, or a list
may be constructed by processing a neighbor list from a different
request that is a superset of the requested list. The neighbor list
build is then :doc:`processed in parallel <Developer_par_neigh>`.
The most commonly required neighbor list is a so-called "half" neighbor
list, where each pair of atoms is listed only once (except when the
:doc:`newton command setting <newton>` for pair is off; in that case
pairs straddling sub-domains or periodic boundaries will be listed twice).
Thus these are the default settings when a neighbor list request is created in:
.. code-block:: C++
void Pair::init_style()
{
neighbor->add_request(this);
}
void Pair::init_list(int /*id*/, NeighList *ptr)
{
list = ptr;
}
The ``this`` pointer argument is required so the neighbor list code can
access the requesting class instance to store the assembled neighbor
list with that instance by calling its ``init_list()`` member function.
The optional second argument (omitted here) contains a bitmask of flags
that determines the kind of neighbor list requested. The default value
used here asks for a perpetual "half" neighbor list.
Non-default values of the second argument need to be used to adjust a
neighbor list request to the specific needs of a style an additional
request flag is needed. The :doc:`tersoff <pair_tersoff>` pair style,
for example, needs a "full" neighbor list:
.. code-block:: C++
void PairTersoff::init_style()
{
// [...]
neighbor->add_request(this, NeighConst::REQ_FULL);
}
When a pair style supports r-RESPA time integration with different cutoff regions,
the request flag may depend on the corresponding r-RESPA settings. Here an example
from pair style lj/cut:
.. code-block:: C++
void PairLJCut::init_style()
{
int list_style = NeighConst::REQ_DEFAULT;
if (update->whichflag == 1 && utils::strmatch(update->integrate_style, "^respa")) {
auto respa = (Respa *) update->integrate;
if (respa->level_inner >= 0) list_style = NeighConst::REQ_RESPA_INOUT;
if (respa->level_middle >= 0) list_style = NeighConst::REQ_RESPA_ALL;
}
neighbor->add_request(this, list_style);
// [...]
}
Granular pair styles need neighbor lists based on particle sizes and not cutoff
and also may require to have the list of previous neighbors available ("history").
For example with:
.. code-block:: C++
if (use_history) neighbor->add_request(this, NeighConst::REQ_SIZE | NeighConst::REQ_HISTORY);
else neighbor->add_request(this, NeighConst::REQ_SIZE);
In case a class would need to make multiple neighbor list requests with different
settings each request can set an id which is then used in the corresponding
``init_list()`` function to assign it to the suitable pointer variable. This is
done for example by the :doc:`pair style meam <pair_meam>`:
.. code-block:: C++
void PairMEAM::init_style()
{
// [...]
neighbor->add_request(this, NeighConst::REQ_FULL)->set_id(1);
neighbor->add_request(this)->set_id(2);
}
void PairMEAM::init_list(int id, NeighList *ptr)
{
if (id == 1) listfull = ptr;
else if (id == 2) listhalf = ptr;
}
Fixes may require a neighbor list that is only build occasionally (or
just once) and this can also be indicated by a flag. As an example here
is the request from the ``FixPeriNeigh`` class which is created
internally by :doc:`Peridynamics pair styles <pair_peri>`:
.. code-block:: C++
neighbor->add_request(this, NeighConst::REQ_FULL | NeighConst::REQ_OCCASIONAL);
It is also possible to request a neighbor list that uses a different cutoff
than what is usually inferred from the pair style settings (largest cutoff of
all pair styles plus neighbor list skin). The following is used in the
:doc:`compute rdf <compute_rdf>` command implementation:
.. code-block:: C++
if (cutflag)
neighbor->add_request(this, NeighConst::REQ_OCCASIONAL)->set_cutoff(mycutneigh);
else
neighbor->add_request(this, NeighConst::REQ_OCCASIONAL);
The neighbor list request function has a slightly different set of arguments
when created by a command style. In this case the neighbor list is
*always* an occasional neighbor list, so that flag is not needed. However
for printing the neighbor list summary the name of the requesting command
should be set. Below is the request from the :doc:`delete atoms <delete_atoms>`
command:
.. code-block:: C++
neighbor->add_request(this, "delete_atoms", NeighConst::REQ_FULL);
Fix contributions to instantaneous energy, virial, and cumulative energy
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

8
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@ -225,7 +225,7 @@ follows:
commands in an input script.
- The Force class computes various forces between atoms. The Pair
parent class is for non-bonded or pair-wise forces, which in LAMMPS
parent class is for non-bonded or pairwise forces, which in LAMMPS
also includes many-body forces such as the Tersoff 3-body potential if
those are computed by walking pairwise neighbor lists. The Bond,
Angle, Dihedral, Improper parent classes are styles for bonded
@ -252,12 +252,6 @@ follows:
- The Timer class logs timing information, output at the end
of a run.
.. TODO section on "Spatial decomposition and parallel operations"
.. diagram of 3d processor grid, brick vs. tiled. local vs. ghost
.. atoms, 6-way communication with pack/unpack functions,
.. PBC as part of the communication, forward and reverse communication
.. rendezvous communication, ring communication.
.. TODO section on "Fixes, Computes, and Variables"
.. how and when data is computed and provided and how it is
.. referenced. flags in Fix/Compute/Variable classes tell

49
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@ -8,11 +8,20 @@ without recompiling LAMMPS. The functionality for this and the
Plugins use the operating system's capability to load dynamic shared
object (DSO) files in a way similar shared libraries and then reference
specific functions in those DSOs. Any DSO file with plugins has to include
an initialization function with a specific name, "lammpsplugin_init", that
has to follow specific rules described below. When loading the DSO with
the "plugin" command, this function is looked up and called and will then
register the contained plugin(s) with LAMMPS.
specific functions in those DSOs. Any DSO file with plugins has to
include an initialization function with a specific name,
"lammpsplugin_init", that has to follow specific rules described below.
When loading the DSO with the "plugin" command, this function is looked
up and called and will then register the contained plugin(s) with
LAMMPS.
When the environment variable ``LAMMPS_PLUGIN_PATH`` is set, then LAMMPS
will search the directory (or directories) listed in this path for files
with names that end in ``plugin.so`` (e.g. ``helloplugin.so``) and will
try to load the contained plugins automatically at start-up. For
plugins that are loaded this way, the behavior of LAMMPS should be
identical to a binary where the corresponding code was compiled in
statically as a package.
From the programmer perspective this can work because of the object
oriented design of LAMMPS where all pair style commands are derived from
@ -65,19 +74,18 @@ Members of ``lammpsplugin_t``
* - handle
- Pointer to the open DSO file handle
Only one of the three alternate creator entries can be used at a time
and which of those is determined by the style of plugin. The
"creator.v1" element is for factory functions of supported styles
computing forces (i.e. command, pair, bond, angle, dihedral, or
improper styles) and the function takes as single argument the pointer
to the LAMMPS instance. The factory function is cast to the
``lammpsplugin_factory1`` type before assignment. The "creator.v2"
element is for factory functions creating an instance of a fix, compute,
or region style and takes three arguments: a pointer to the LAMMPS
instance, an integer with the length of the argument list and a ``char
**`` pointer to the list of arguments. The factory function pointer
needs to be cast to the ``lammpsplugin_factory2`` type before
assignment.
Only one of the two alternate creator entries can be used at a time and
which of those is determined by the style of plugin. The "creator.v1"
element is for factory functions of supported styles computing forces
(i.e. pair, bond, angle, dihedral, or improper styles) or command styles
and the function takes as single argument the pointer to the LAMMPS
instance. The factory function is cast to the ``lammpsplugin_factory1``
type before assignment. The "creator.v2" element is for factory
functions creating an instance of a fix, compute, or region style and
takes three arguments: a pointer to the LAMMPS instance, an integer with
the length of the argument list and a ``char **`` pointer to the list of
arguments. The factory function pointer needs to be cast to the
``lammpsplugin_factory2`` type before assignment.
Pair style example
^^^^^^^^^^^^^^^^^^
@ -249,3 +257,8 @@ by ``#ifdef PAIR_CLASS`` is not needed, since the mapping of the class
name to the style name is done by the plugin registration function with
the information from the ``lammpsplugin_t`` struct. It may be included
in case the new code is intended to be later included in LAMMPS directly.
A plugin may be registered under an existing style name. In that case
the plugin will override the existing code. This can be used to modify
the behavior of existing styles or to debug new versions of them without
having to re-compile or re-install all of LAMMPS.

101
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@ -21,18 +21,21 @@ In that case, the functions will stop with an error message, indicating
the name of the problematic file, if possible unless the *error* argument
is a NULL pointer.
The :cpp:func:`fgets_trunc` function will work similar for ``fgets()``
but it will read in a whole line (i.e. until the end of line or end
of file), but store only as many characters as will fit into the buffer
including a final newline character and the terminating NULL byte.
If the line in the file is longer it will thus be truncated in the buffer.
This function is used by :cpp:func:`read_lines_from_file` to read individual
lines but make certain they follow the size constraints.
The :cpp:func:`utils::fgets_trunc() <LAMMPS_NS::utils::fgets_trunc>`
function will work similar for ``fgets()`` but it will read in a whole
line (i.e. until the end of line or end of file), but store only as many
characters as will fit into the buffer including a final newline
character and the terminating NULL byte. If the line in the file is
longer it will thus be truncated in the buffer. This function is used
by :cpp:func:`utils::read_lines_from_file()
<LAMMPS_NS::utils::read_lines_from_file>` to read individual lines but
make certain they follow the size constraints.
The :cpp:func:`read_lines_from_file` function will read the requested
number of lines of a maximum length into a buffer and will return 0
if successful or 1 if not. It also guarantees that all lines are
terminated with a newline character and the entire buffer with a
The :cpp:func:`utils::read_lines_from_file()
<LAMMPS_NS::utils::read_lines_from_file>` function will read the
requested number of lines of a maximum length into a buffer and will
return 0 if successful or 1 if not. It also guarantees that all lines
are terminated with a newline character and the entire buffer with a
NULL character.
----------
@ -56,13 +59,13 @@ String to number conversions with validity check
These functions should be used to convert strings to numbers. They are
are strongly preferred over C library calls like ``atoi()`` or
``atof()`` since they check if the **entire** provided string is a valid
``atof()`` since they check if the **entire** string is a valid
(floating-point or integer) number, and will error out instead of
silently returning the result of a partial conversion or zero in cases
where the string is not a valid number. This behavior allows to more
easily detect typos or issues when processing input files.
where the string is not a valid number. This behavior improves
detecting typos or issues when processing input files.
Similarly the :cpp:func:`logical() <LAMMPS_NS::utils::logical>` function
Similarly the :cpp:func:`utils::logical() <LAMMPS_NS::utils::logical>` function
will convert a string into a boolean and will only accept certain words.
The *do_abort* flag should be set to ``true`` in case this function
@ -70,25 +73,40 @@ is called only on a single MPI rank, as that will then trigger the
a call to ``Error::one()`` for errors instead of ``Error::all()``
and avoids a "hanging" calculation when run in parallel.
Please also see :cpp:func:`is_integer() <LAMMPS_NS::utils::is_integer>`
and :cpp:func:`is_double() <LAMMPS_NS::utils::is_double>` for testing
Please also see :cpp:func:`utils::is_integer() <LAMMPS_NS::utils::is_integer>`
and :cpp:func:`utils::is_double() <LAMMPS_NS::utils::is_double>` for testing
strings for compliance without conversion.
----------
.. doxygenfunction:: numeric
.. doxygenfunction:: numeric(const char *file, int line, const std::string &str, bool do_abort, LAMMPS *lmp)
:project: progguide
.. doxygenfunction:: inumeric
.. doxygenfunction:: numeric(const char *file, int line, const char *str, bool do_abort, LAMMPS *lmp)
:project: progguide
.. doxygenfunction:: bnumeric
.. doxygenfunction:: inumeric(const char *file, int line, const std::string &str, bool do_abort, LAMMPS *lmp)
:project: progguide
.. doxygenfunction:: tnumeric
.. doxygenfunction:: inumeric(const char *file, int line, const char *str, bool do_abort, LAMMPS *lmp)
:project: progguide
.. doxygenfunction:: logical
.. doxygenfunction:: bnumeric(const char *file, int line, const std::string &str, bool do_abort, LAMMPS *lmp)
:project: progguide
.. doxygenfunction:: bnumeric(const char *file, int line, const char *str, bool do_abort, LAMMPS *lmp)
:project: progguide
.. doxygenfunction:: tnumeric(const char *file, int line, const std::string &str, bool do_abort, LAMMPS *lmp)
:project: progguide
.. doxygenfunction:: tnumeric(const char *file, int line, const char *str, bool do_abort, LAMMPS *lmp)
:project: progguide
.. doxygenfunction:: logical(const char *file, int line, const std::string &str, bool do_abort, LAMMPS *lmp)
:project: progguide
.. doxygenfunction:: logical(const char *file, int line, const char *str, bool do_abort, LAMMPS *lmp)
:project: progguide
@ -190,6 +208,9 @@ Convenience functions
.. doxygenfunction:: logmesg(LAMMPS *lmp, const std::string &mesg)
:project: progguide
.. doxygenfunction:: flush_buffers(LAMMPS *lmp)
:project: progguide
.. doxygenfunction:: getsyserror
:project: progguide
@ -322,11 +343,11 @@ This code example should produce the following output:
.. doxygenclass:: LAMMPS_NS::InvalidIntegerException
:project: progguide
:members: what
:members:
.. doxygenclass:: LAMMPS_NS::InvalidFloatException
:project: progguide
:members: what
:members:
----------
@ -375,21 +396,26 @@ A typical code segment would look like this:
----------
.. _file-reader-classes:
File reader classes
-------------------
The purpose of the file reader classes is to simplify the recurring task
of reading and parsing files. They can use the
:cpp:class:`LAMMPS_NS::ValueTokenizer` class to process the read in
text. The :cpp:class:`LAMMPS_NS::TextFileReader` is a more general
version while :cpp:class:`LAMMPS_NS::PotentialFileReader` is specialized
to implement the behavior expected for looking up and reading/parsing
files with potential parameters in LAMMPS. The potential file reader
class requires a LAMMPS instance, requires to be run on MPI rank 0 only,
will use the :cpp:func:`LAMMPS_NS::utils::get_potential_file_path`
function to look up and open the file, and will call the
:cpp:class:`LAMMPS_NS::Error` class in case of failures to read or to
convert numbers, so that LAMMPS will be aborted.
:cpp:class:`ValueTokenizer <LAMMPS_NS::ValueTokenizer>` class to process
the read in text. The :cpp:class:`TextFileReader
<LAMMPS_NS::TextFileReader>` is a more general version while
:cpp:class:`PotentialFileReader <LAMMPS_NS::PotentialFileReader>` is
specialized to implement the behavior expected for looking up and
reading/parsing files with potential parameters in LAMMPS. The
potential file reader class requires a LAMMPS instance, requires to be
run on MPI rank 0 only, will use the
:cpp:func:`utils::get_potential_file_path
<LAMMPS_NS::utils::get_potential_file_path>` function to look up and
open the file, and will call the :cpp:class:`LAMMPS_NS::Error` class in
case of failures to read or to convert numbers, so that LAMMPS will be
aborted.
.. code-block:: C++
:caption: Use of PotentialFileReader class in pair style coul/streitz
@ -464,10 +490,10 @@ provided, as that is used to determine whether a new page of memory
must be used.
The :cpp:class:`MyPage <LAMMPS_NS::MyPage>` class offers two ways to
reserve a chunk: 1) with :cpp:func:`get() <LAMMPS_NS::MyPage::get>` the
chunk size needs to be known in advance, 2) with :cpp:func:`vget()
reserve a chunk: 1) with :cpp:func:`MyPage::get() <LAMMPS_NS::MyPage::get>` the
chunk size needs to be known in advance, 2) with :cpp:func:`MyPage::vget()
<LAMMPS_NS::MyPage::vget>` a pointer to the next chunk is returned, but
its size is registered later with :cpp:func:`vgot()
its size is registered later with :cpp:func:`MyPage::vgot()
<LAMMPS_NS::MyPage::vgot>`.
.. code-block:: C++
@ -570,4 +596,3 @@ the communication buffers.
.. doxygenunion:: LAMMPS_NS::ubuf
:project: progguide

2
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@ -55,7 +55,7 @@ of each timestep. First of all, implement a constructor:
if (narg < 4)
error->all(FLERR,"Illegal fix print/vel command");
nevery = force->inumeric(FLERR,arg[3]);
nevery = utils::inumeric(FLERR,arg[3],false,lmp);
if (nevery <= 0)
error->all(FLERR,"Illegal fix print/vel command");
}

10
doc/src/Errors_messages.rst
View File

@ -1941,6 +1941,9 @@ Doc page with :doc:`WARNING messages <Errors_warnings>`
*Compute ID for fix numdiff does not exist*
Self-explanatory.
*Compute ID for fix numdiff/virial does not exist*
Self-explanatory.
*Compute ID for fix store/state does not exist*
Self-explanatory.
@ -3796,6 +3799,10 @@ Doc page with :doc:`WARNING messages <Errors_warnings>`
Self-explanatory. Efficient loop over all atoms for numerical
difference requires consecutive atom IDs.
*Fix numdiff/virial must use group all*
Virial contributions computed by this fix are
computed on all atoms.
*Fix nve/asphere requires extended particles*
This fix can only be used for particles with a shape setting.
@ -7800,9 +7807,6 @@ keyword to allow for additional bonds to be formed
The system size must fit in a 32-bit integer to use this dump
style.
*Too many atoms to dump sort*
Cannot sort when running with more than 2\^31 atoms.
*Too many elements extracted from MEAM library.*
Increase 'maxelt' in meam.h and recompile.

2
doc/src/Errors_warnings.rst
View File

@ -416,7 +416,7 @@ This will most likely cause errors in kinetic fluctuations.
not defined for the specified atom style.
*Molecule has bond topology but no special bond settings*
This means the bonded atoms will not be excluded in pair-wise
This means the bonded atoms will not be excluded in pairwise
interactions.
*Molecule template for create_atoms has multiple molecules*

5
doc/src/Howto_drude2.rst
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@ -491,11 +491,6 @@ NPT ensemble using Nose-Hoover thermostat:
**(Schroeder)** Schroeder and Steinhauser, J Chem Phys, 133,
154511 (2010).
.. _Jiang2:
**(Jiang)** Jiang, Hardy, Phillips, MacKerell, Schulten, and Roux,
J Phys Chem Lett, 2, 87-92 (2011).
.. _Thole2:
**(Thole)** Chem Phys, 59, 341 (1981).

2
doc/src/Howto_pylammps.rst
View File

@ -545,6 +545,6 @@ Feedback and Contributing
-------------------------
If you find this Python interface useful, please feel free to provide feedback
and ideas on how to improve it to Richard Berger (richard.berger@temple.edu). We also
and ideas on how to improve it to Richard Berger (richard.berger@outlook.com). We also
want to encourage people to write tutorial style IPython notebooks showcasing LAMMPS usage
and maybe their latest research results.

55
doc/src/Howto_structured_data.rst
View File

@ -21,7 +21,8 @@ YAML
print """---
timestep: $(step)
pe: $(pe)
ke: $(ke)""" file current_state.yaml screen no
ke: $(ke)
...""" file current_state.yaml screen no
.. code-block:: yaml
:caption: current_state.yaml
@ -51,6 +52,58 @@ JSON
"ke": 2.4962152903997174569
}
YAML format thermo_style output
===============================
.. versionadded:: 24Mar2022
LAMMPS supports the thermo style "yaml" and for "custom" style
thermodynamic output the format can be changed to YAML with
:doc:`thermo_modify line yaml <thermo_modify>`. This will produce a
block of output in a compact YAML format - one "document" per run - of
the following style:
.. code-block:: yaml
---
keywords: [Step, Temp, E_pair, E_mol, TotEng, Press, ]
data:
- [100, 0.757453103239935, -5.7585054860159, 0, -4.62236133677021, 0.207261053624721, ]
- [110, 0.759322359337036, -5.7614668389562, 0, -4.62251889318624, 0.194314975399602, ]
- [120, 0.759372342462676, -5.76149365656489, 0, -4.62247073844943, 0.191600048851267, ]
- [130, 0.756833027516501, -5.75777334823494, 0, -4.62255928350835, 0.208792327853067, ]
...
This data can be extracted and parsed from a log file using python with:
.. code-block:: python
import re, yaml
docs = ""
with open("log.lammps") as f:
for line in f:
m = re.search(r"^(keywords:.*$|data:$|---$|\.\.\.$| - \[.*\]$)", line)
if m: docs += m.group(0) + '\n'
thermo = list(yaml.load_all(docs, Loader=yaml.SafeLoader))
print("Number of runs: ", len(thermo))
print(thermo[1]['keywords'][4], ' = ', thermo[1]['data'][2][4])
After loading the YAML data, `thermo` is a list containing a dictionary
for each "run" where the tag "keywords" maps to the list of thermo
header strings and the tag "data" has a list of lists where the outer
list represents the lines of output and the inner list the values of the
columns matching the header keywords for that step. The second print()
command for example will print the header string for the fifth keyword
of the second run and the corresponding value for the third output line
of that run:
.. parsed-literal::
Number of runs: 2
TotEng = -4.62140097780047
Writing continuous data during a simulation
===========================================

3
doc/src/Install_git.rst
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@ -165,5 +165,4 @@ changed. How to do this depends on the build system you are using.
URL "git@github.com:lammps/lammps.git".
The LAMMPS GitHub project is currently managed by Axel Kohlmeyer
(Temple U, akohlmey at gmail.com) and Richard Berger (Temple U,
richard.berger at temple.edu).
(Temple U, akohlmey at gmail.com).

2
doc/src/Intro_authors.rst
View File

@ -8,7 +8,7 @@ University:
* Aidan Thompson, athomps at sandia.gov
* Stan Moore, stamoor at sandia.gov
* Axel Kohlmeyer, akohlmey at gmail.com
* Richard Berger, richard.berger at temple.edu
* Richard Berger, richard.berger at outlook.com
.. _sjp: http://www.cs.sandia.gov/~sjplimp
.. _lws: https://www.lammps.org

6
doc/src/Library_utility.rst
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@ -13,6 +13,7 @@ functions. They do not directly call the LAMMPS library.
- :cpp:func:`lammps_fix_external_set_virial_peratom`
- :cpp:func:`lammps_fix_external_set_vector_length`
- :cpp:func:`lammps_fix_external_set_vector`
- :cpp:func:`lammps_flush_buffers`
- :cpp:func:`lammps_free`
- :cpp:func:`lammps_is_running`
- :cpp:func:`lammps_force_timeout`
@ -72,6 +73,11 @@ where such memory buffers were allocated that require the use of
-----------------------
.. doxygenfunction:: lammps_flush_buffers
:project: progguide
-----------------------
.. doxygenfunction:: lammps_free
:project: progguide

17
doc/src/Modify.rst
View File

@ -1,16 +1,17 @@
Modifying & extending LAMMPS
****************************
LAMMPS is designed in a modular fashion so as to be easy to modify and
LAMMPS is designed in a modular fashion and to be easy to modify or
extend with new functionality. In fact, about 95% of its source code
is add-on files. These doc pages give basic instructions on how to do
this.
are optional. The following pages give basic instructions on what
is required when adding new styles of different kinds to LAMMPS.
If you add a new feature to LAMMPS and think it will be of interest to
general users, we encourage you to submit it for inclusion in LAMMPS
as a pull request on our `GitHub site <https://github.com/lammps/lammps>`_,
after reading about :doc:`how to prepare your code for submission <Modify_contribute>`
and :doc:`the style requirements and recommendations <Modify_style>`.
If you add a new feature to LAMMPS and think it will be of general
interest to other users, we encourage you to submit it for inclusion in
LAMMPS as a pull request on our `GitHub site
<https://github.com/lammps/lammps>`_, after reading about :doc:`how to
prepare your code for submission <Modify_contribute>` and :doc:`the
style requirements and recommendations <Modify_style>`.
.. toctree::
:maxdepth: 1

15
doc/src/Modify_overview.rst
View File

@ -1,13 +1,14 @@
Overview
========
The best way to add a new feature to LAMMPS is to find a similar
feature and look at the corresponding source and header files to figure
out what it does. You will need some knowledge of C++ to be able to
understand the high-level structure of LAMMPS and its class
organization, but functions (class methods) that do actual
computations are written in vanilla C-style code and operate on simple
C-style data structures (vectors and arrays).
The best way to add a new feature to LAMMPS is to find a similar feature
and look at the corresponding source and header files to figure out what
it does. You will need some knowledge of C++ to be able to understand
the high-level structure of LAMMPS and its class organization, but
functions (class methods) that do actual computations are mostly written
in C-style code and operate on simple C-style data structures (vectors
and arrays). A high-level overview of the programming style choices in
LAMMPS is :doc:`given elsewhere <Developer_code_design>`.
Most of the new features described on the :doc:`Modify <Modify>` doc
page require you to write a new C++ derived class (except for exceptions

22
doc/src/Modify_pair.rst
View File

@ -12,24 +12,24 @@ includes some optional methods to enable its use with rRESPA.
Here is a brief description of the class methods in pair.h:
+---------------------------------+-------------------------------------------------------------------+
+---------------------------------+---------------------------------------------------------------------+
| compute | workhorse routine that computes pairwise interactions |
+---------------------------------+-------------------------------------------------------------------+
+---------------------------------+---------------------------------------------------------------------+
| settings | reads the input script line with arguments you define |
+---------------------------------+-------------------------------------------------------------------+
+---------------------------------+---------------------------------------------------------------------+
| coeff | set coefficients for one i,j type pair |
+---------------------------------+-------------------------------------------------------------------+
+---------------------------------+---------------------------------------------------------------------+
| init_one | perform initialization for one i,j type pair |
+---------------------------------+-------------------------------------------------------------------+
+---------------------------------+---------------------------------------------------------------------+
| init_style | initialization specific to this pair style |
+---------------------------------+-------------------------------------------------------------------+
+---------------------------------+---------------------------------------------------------------------+
| write & read_restart | write/read i,j pair coeffs to restart files |
+---------------------------------+-------------------------------------------------------------------+
+---------------------------------+---------------------------------------------------------------------+
| write & read_restart_settings | write/read global settings to restart files |
+---------------------------------+-------------------------------------------------------------------+
| single | force and energy of a single pairwise interaction between 2 atoms |
+---------------------------------+-------------------------------------------------------------------+
+---------------------------------+---------------------------------------------------------------------+
| single | force/r and energy of a single pairwise interaction between 2 atoms |
+---------------------------------+---------------------------------------------------------------------+
| compute_inner/middle/outer | versions of compute used by rRESPA |
+---------------------------------+-------------------------------------------------------------------+
+---------------------------------+---------------------------------------------------------------------+
The inner/middle/outer routines are optional.

51
doc/src/Modify_style.rst
View File

@ -250,9 +250,11 @@ keep the code readable to programmers that have limited C++ programming
experience. C++ constructs are acceptable when they help improving the
readability and reliability of the code, e.g. when using the
`std::string` class instead of manipulating pointers and calling the
string functions of the C library. In addition and number of convenient
:doc:`utility functions and classes <Developer_utils>` for recurring
tasks are provided.
string functions of the C library. In addition a collection of
convenient :doc:`utility functions and classes <Developer_utils>` for
recurring tasks and a collection of
:doc:`platform neutral functions <Developer_platform>` for improved
portability are provided.
Included Fortran code has to be compatible with the Fortran 2003
standard. Python code must be compatible with Python 3.5. Large parts
@ -261,10 +263,11 @@ compatible with Python 2.7. Compatibility with Python 2.7 is
desirable, but compatibility with Python 3.5 is **required**.
Compatibility with these older programming language standards is very
important to maintain portability, especially with HPC cluster
environments, which tend to be running older software stacks and LAMMPS
users may be required to use those older tools or not have the option to
install newer compilers.
important to maintain portability and availability of LAMMPS on many
platforms. This applies especially to HPC cluster environments, which
tend to be running older software stacks and LAMMPS users may be
required to use those older tools for access to advanced hardware
features or not have the option to install newer compilers or libraries.
Programming conventions (varied)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@ -305,6 +308,40 @@ you are uncertain, please ask.
FILE pointers and only be done on MPI rank 0. Use the :cpp:func:`utils::logmesg`
convenience function where possible.
- Usage of C++11 `virtual`, `override`, `final` keywords: Please follow the
`C++ Core Guideline C.128 <https://isocpp.github.io/CppCoreGuidelines/CppCoreGuidelines#Rh-override>`_.
That means, you should only use `virtual` to declare a new virtual
function, `override` to indicate you are overriding an existing virtual
function, and `final` to prevent any further overriding.
- Trivial destructors: Prefer not writing destructors when they are empty and `default`.
.. code-block:: c++
// don't write destructors for A or B like this
class A : protected Pointers {
public:
A();
~A() override {}
};
class B : protected Pointers {
public:
B();
~B() override = default;
};
// instead, let the compiler create the implicit default destructor by not writing it
class A : protected Pointers {
public:
A();
};
class B : protected Pointers {
public:
B();
};
- Header files, especially those defining a "style", should only use
the absolute minimum number of include files and **must not** contain
any ``using`` statements. Typically that would be only the header for

67
doc/src/Modify_thermo.rst
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@ -1,27 +1,54 @@
Thermodynamic output options
============================
There is one class that computes and prints thermodynamic information
to the screen and log file; see the file thermo.cpp.
The ``Thermo`` class computes and prints thermodynamic information to
the screen and log file; see the files ``thermo.cpp`` and ``thermo.h``.
There are two styles defined in thermo.cpp: "one" and "multi". There
is also a flexible "custom" style which allows the user to explicitly
list keywords for quantities to print when thermodynamic info is
output. See the :doc:`thermo_style <thermo_style>` command for a list
of defined quantities.
There are four styles defined in ``thermo.cpp``: "one", "multi", "yaml",
and "custom". The "custom" style allows the user to explicitly list
keywords for individual quantities to print when thermodynamic output is
generated. The others have a fixed list of keywords. See the
:doc:`thermo_style <thermo_style>` command for a list of available
quantities. The formatting of the "custom" style defaults to the "one"
style, but can be adapted using :doc:`thermo_modify line <thermo_modify>`.
The thermo styles (one, multi, etc) are simply lists of keywords.
Adding a new style thus only requires defining a new list of keywords.
Search for the word "customize" with references to "thermo style" in
thermo.cpp to see the two locations where code will need to be added.
The thermo styles (one, multi, etc) are defined by lists of keywords
with associated formats for integer and floating point numbers and
identified but an enumerator constant. Adding a new style thus mostly
requires defining a new list of keywords and the associated formats and
then inserting the required output processing where the enumerators are
identified. Search for the word "CUSTOMIZATION" with references to
"thermo style" in the ``thermo.cpp`` file to see the locations where
code will need to be added. The member function ``Thermo::header()``
prints output at the very beginning of a thermodynamic output block and
can be used to print column headers or other front matter. The member
function ``Thermo::footer()`` prints output at the end of a
thermodynamic output block. The formatting of the output is done by
assembling a "line" (which may span multiple lines if the style inserts
newline characters ("\n" as in the "multi" style).
New keywords can also be added to thermo.cpp to compute new quantities
for output. Search for the word "customize" with references to
"keyword" in thermo.cpp to see the several locations where code will
need to be added.
New thermodynamic keywords can also be added to ``thermo.cpp`` to
compute new quantities for output. Search for the word "CUSTOMIZATION"
with references to "keyword" in ``thermo.cpp`` to see the several
locations where code will need to be added. Effectively, you need to
define a member function that computes the property, add an if statement
in ``Thermo::parse_fields()`` where the corresponding header string for
the keyword and the function pointer is registered by calling the
``Thermo::addfield()`` method, and add an if statement in
``Thermo::evaluate_keyword()`` which is called from the ``Variable``
class when a thermo keyword is encountered.
Note that the :doc:`thermo_style custom <thermo_style>` command already allows
for thermo output of quantities calculated by :doc:`fixes <fix>`,
:doc:`computes <compute>`, and :doc:`variables <variable>`. Thus, it may
be simpler to compute what you wish via one of those constructs, than
by adding a new keyword to the thermo command.
.. note::
The third argument to ``Thermo::addfield()`` is a flag indicating
whether the function for the keyword computes a floating point
(FLOAT), regular integer (INT), or big integer (BIGINT) value. This
information is used for formatting the thermodynamic output. Inside
the function the result must then be stored either in the ``dvalue``,
``ivalue`` or ``bivalue`` member variable, respectively.
Since the :doc:`thermo_style custom <thermo_style>` command allows to
use output of quantities calculated by :doc:`fixes <fix>`,
:doc:`computes <compute>`, and :doc:`variables <variable>`, it may often
be simpler to compute what you wish via one of those constructs, rather
than by adding a new keyword to the thermo_style command.

19
doc/src/Modify_variable.rst
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@ -1,8 +1,8 @@
Variable options
================
There is one class that computes and stores :doc:`variable <variable>`
information in LAMMPS; see the file variable.cpp. The value
The ``Variable`` class computes and stores :doc:`variable <variable>`
information in LAMMPS; see the file ``variable.cpp``. The value
associated with a variable can be periodically printed to the screen
via the :doc:`print <print>`, :doc:`fix print <fix_print>`, or
:doc:`thermo_style custom <thermo_style>` commands. Variables of style
@ -19,21 +19,22 @@ of arguments:
compute values = c_mytemp[0], c_thermo_press[3], ...
Adding keywords for the :doc:`thermo_style custom <thermo_style>`
command (which can then be accessed by variables) is discussed on the
:doc:`Modify thermo <Modify_thermo>` doc page.
command (which can then be accessed by variables) is discussed in the
:doc:`Modify thermo <Modify_thermo>` documentation.
Adding a new math function of one or two arguments can be done by
editing one section of the Variable::evaluate() method. Search for
editing one section of the ``Variable::evaluate()`` method. Search for
the word "customize" to find the appropriate location.
Adding a new group function can be done by editing one section of the
Variable::evaluate() method. Search for the word "customize" to find
the appropriate location. You may need to add a new method to the
Group class as well (see the group.cpp file).
``Variable::evaluate()`` method. Search for the word "customize" to
find the appropriate location. You may need to add a new method to the
Group class as well (see the ``group.cpp`` file).
Accessing a new atom-based vector can be done by editing one section
of the Variable::evaluate() method. Search for the word "customize"
to find the appropriate location.
Adding new :doc:`compute styles <compute>` (whose calculated values can
then be accessed by variables) is discussed on the :doc:`Modify compute <Modify_compute>` doc page.
then be accessed by variables) is discussed in the :doc:`Modify compute
<Modify_compute>` documentation.

13
doc/src/Packages_details.rst
View File

@ -9,7 +9,7 @@ gives links to documentation, example scripts, and pictures/movies (if
available) that illustrate use of the package.
The majority of packages can be included in a LAMMPS build with a
single setting (``-D PGK_<NAME>=on`` for CMake) or command
single setting (``-D PKG_<NAME>=on`` for CMake) or command
(``make yes-<name>`` for make). See the :doc:`Build package <Build_package>`
page for more info. A few packages may require additional steps;
this is indicated in the descriptions below. The :doc:`Build extras <Build_extras>`
@ -1880,6 +1880,12 @@ MPIIO library. It adds :doc:`dump styles <dump>` with a "mpiio" in
their style name. Restart files with an ".mpiio" suffix are also
written and read in parallel.
.. warning::
The MPIIO package is currently unmaintained and has become
unreliable. Use with caution.
**Install:**
The MPIIO package requires that LAMMPS is build in :ref:`MPI parallel mode <serial>`.
@ -2148,6 +2154,11 @@ A :doc:`plugin <plugin>` command that can load and unload several
kind of styles in LAMMPS from shared object files at runtime without
having to recompile and relink LAMMPS.
When the environment variable ``LAMMPS_PLUGIN_PATH`` is set, then LAMMPS
will search the directory (or directories) listed in this path for files
with names that end in ``plugin.so`` (e.g. ``helloplugin.so``) and will
try to load the contained plugins automatically at start-up.
**Authors:** Axel Kohlmeyer (Temple U)
**Supporting info:**

102
doc/src/Python_install.rst
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@ -25,11 +25,10 @@ Installing the LAMMPS Python Module and Shared Library
======================================================
Making LAMMPS usable within Python and vice versa requires putting the
LAMMPS Python package (``lammps``) into a location where the
Python interpreter can find it and installing the LAMMPS shared library
into a folder that the dynamic loader searches or inside of the installed
``lammps`` package folder. There are multiple ways to achieve
this.
LAMMPS Python package (``lammps``) into a location where the Python
interpreter can find it and installing the LAMMPS shared library into a
folder that the dynamic loader searches or inside of the installed
``lammps`` package folder. There are multiple ways to achieve this.
#. Do a full LAMMPS installation of libraries, executables, selected
headers, documentation (if enabled), and supporting files (only
@ -159,38 +158,52 @@ this.
make install-python
This will try to install (only) the shared library and the Python
package into a system folder and if that fails (due to missing
write permissions) will instead do the installation to a user
folder under ``$HOME/.local``. For a system-wide installation you
This will try to build a so-called (binary) 'wheel', a compressed
binary python package and then install it with the python package
manager 'pip'. Installation will be attempted into a system-wide
``site-packages`` folder and if that fails into the corresponding
folder in the user's home directory. For a system-wide installation you
would have to gain superuser privilege, e.g. though ``sudo``
+------------------------+-----------------------------------------------------------------+-------------------------------------------------------------+
+------------------------+----------------------------------------------------------+-------------------------------------------------------------+
| File | Location | Notes |
+========================+=================================================================+=============================================================+
| LAMMPS Python package | * ``$HOME/.local/lib/pythonX.Y/site-packages/lammps`` (32bit) | ``X.Y`` depends on the installed Python version |
| | * ``$HOME/.local/lib64/pythonX.Y/site-packages/lammps`` (64bit) | |
+------------------------+-----------------------------------------------------------------+-------------------------------------------------------------+
| LAMMPS shared library | * ``$HOME/.local/lib/pythonX.Y/site-packages/lammps`` (32bit) | ``X.Y`` depends on the installed Python version |
| | * ``$HOME/.local/lib64/pythonX.Y/site-packages/lammps`` (64bit) | |
+------------------------+-----------------------------------------------------------------+-------------------------------------------------------------+
+========================+==========================================================+=============================================================+
| LAMMPS Python package | * ``$HOME/.local/lib/pythonX.Y/site-packages/lammps`` | ``X.Y`` depends on the installed Python version |
+------------------------+----------------------------------------------------------+-------------------------------------------------------------+
| LAMMPS shared library | * ``$HOME/.local/lib/pythonX.Y/site-packages/lammps`` | ``X.Y`` depends on the installed Python version |
+------------------------+----------------------------------------------------------+-------------------------------------------------------------+
For a system-wide installation those folders would then become.
+------------------------+---------------------------------------------------------+-------------------------------------------------------------+
+------------------------+-------------------------------------------------+-------------------------------------------------------------+
| File | Location | Notes |
+========================+=========================================================+=============================================================+
| LAMMPS Python package | * ``/usr/lib/pythonX.Y/site-packages/lammps`` (32bit) | ``X.Y`` depends on the installed Python version |
| | * ``/usr/lib64/pythonX.Y/site-packages/lammps`` (64bit) | |
+------------------------+---------------------------------------------------------+-------------------------------------------------------------+
| LAMMPS shared library | * ``/usr/lib/pythonX.Y/site-packages/lammps`` (32bit) | ``X.Y`` depends on the installed Python version |
| | * ``/usr/lib64/pythonX.Y/site-packages/lammps`` (64bit) | |
+------------------------+---------------------------------------------------------+-------------------------------------------------------------+
+========================+=================================================+=============================================================+
| LAMMPS Python package | * ``/usr/lib/pythonX.Y/site-packages/lammps`` | ``X.Y`` depends on the installed Python version |
+------------------------+-------------------------------------------------+-------------------------------------------------------------+
| LAMMPS shared library | * ``/usr/lib/pythonX.Y/site-packages/lammps`` | ``X.Y`` depends on the installed Python version |
+------------------------+-------------------------------------------------+-------------------------------------------------------------+
No environment variables need to be set for those, as those
folders are searched by default by Python or the LAMMPS Python
package.
.. versionchanged:: 24Mar2022
.. note::
If there is an existing installation of the LAMMPS python
module, ``make install-python`` will try to update it.
However, that will fail if the older version of the module
was installed by LAMMPS versions until 17Feb2022. Those
were using the distutils package, which does not create a
"manifest" that allows a clean uninstall. The ``make
install-python`` command will always produce a
lammps-<version>-<python>-<abi>-<os>-<arch>.whl file (the
'wheel'). And this file can be later installed directly with
``python -m pip install <wheel file>.whl`` without having to
type ``make install-python`` again and repeating the build
step, too.
For the traditional make process you can override the python
version to version x.y when calling ``make`` with
``PYTHON=pythonX.Y``. For a CMake based compilation this choice
@ -201,16 +214,12 @@ this.
.. code-block:: bash
$ python install.py -p <python package> -l <shared library> -v <version.h file> [-d <pydir>]
$ python install.py -p <python package> -l <shared library> [-n]
* The ``-p`` flag points to the ``lammps`` Python package folder to be installed,
* the ``-l`` flag points to the LAMMPS shared library file to be installed,
* the ``-v`` flag points to the ``version.h`` file in the LAMMPS source
* and the optional ``-d`` flag to a custom (legacy) installation folder
If you use a legacy installation folder, you will need to set your
``PYTHONPATH`` and ``LD_LIBRARY_PATH`` (and/or ``DYLD_LIBRARY_PATH``) environment
variables accordingly as explained in the description for "In place use".
* and the optional ``-n`` instructs the script to only build a wheel file
but not attempt to install it.
.. tab:: Virtual environment
@ -257,32 +266,29 @@ this.
package and the shared library file are installed into the
following locations:
+------------------------+-----------------------------------------------------------------+-------------------------------------------------------------+
+------------------------+--------------------------------------------------------+-------------------------------------------------------------+
| File | Location | Notes |
+========================+=================================================================+=============================================================+
| LAMMPS Python Module | * ``$VIRTUAL_ENV/lib/pythonX.Y/site-packages/lammps`` (32bit) | ``X.Y`` depends on the installed Python version |
| | * ``$VIRTUAL_ENV/lib64/pythonX.Y/site-packages/lammps`` (64bit) | |
+------------------------+-----------------------------------------------------------------+-------------------------------------------------------------+
| LAMMPS shared library | * ``$VIRTUAL_ENV/lib/pythonX.Y/site-packages/lammps`` (32bit) | ``X.Y`` depends on the installed Python version |
| | * ``$VIRTUAL_ENV/lib64/pythonX.Y/site-packages/lammps`` (64bit) | |
+------------------------+-----------------------------------------------------------------+-------------------------------------------------------------+
+========================+========================================================+=============================================================+
| LAMMPS Python Module | * ``$VIRTUAL_ENV/lib/pythonX.Y/site-packages/lammps`` | ``X.Y`` depends on the installed Python version |
+------------------------+--------------------------------------------------------+-------------------------------------------------------------+
| LAMMPS shared library | * ``$VIRTUAL_ENV/lib/pythonX.Y/site-packages/lammps`` | ``X.Y`` depends on the installed Python version |
+------------------------+--------------------------------------------------------+-------------------------------------------------------------+
If you do a full installation (CMake only) with "install", this
leads to the following installation locations:
+------------------------+-----------------------------------------------------------------+-------------------------------------------------------------+
+------------------------+--------------------------------------------------------+-------------------------------------------------------------+
| File | Location | Notes |
+========================+=================================================================+=============================================================+
| LAMMPS Python Module | * ``$VIRTUAL_ENV/lib/pythonX.Y/site-packages/lammps`` (32bit) | ``X.Y`` depends on the installed Python version |
| | * ``$VIRTUAL_ENV/lib64/pythonX.Y/site-packages/lammps`` (64bit) | |
+------------------------+-----------------------------------------------------------------+-------------------------------------------------------------+
+========================+========================================================+=============================================================+
| LAMMPS Python Module | * ``$VIRTUAL_ENV/lib/pythonX.Y/site-packages/lammps`` | ``X.Y`` depends on the installed Python version |
+------------------------+--------------------------------------------------------+-------------------------------------------------------------+
| LAMMPS shared library | * ``$VIRTUAL_ENV/lib/`` (32bit) | Set shared loader environment variable to this path |
| | * ``$VIRTUAL_ENV/lib64/`` (64bit) | (see below for more info on this) |
+------------------------+-----------------------------------------------------------------+-------------------------------------------------------------+
+------------------------+--------------------------------------------------------+-------------------------------------------------------------+
| LAMMPS executable | * ``$VIRTUAL_ENV/bin/`` | |
+------------------------+-----------------------------------------------------------------+-------------------------------------------------------------+
+------------------------+--------------------------------------------------------+-------------------------------------------------------------+
| LAMMPS potential files | * ``$VIRTUAL_ENV/share/lammps/potentials/`` | Set ``LAMMPS_POTENTIALS`` environment variable to this path |
+------------------------+-----------------------------------------------------------------+-------------------------------------------------------------+
+------------------------+--------------------------------------------------------+-------------------------------------------------------------+
In that case you need to modify the ``$HOME/myenv/bin/activate``
script in a similar fashion you need to update your

4
doc/src/Run_output.rst
View File

@ -106,7 +106,7 @@ individual ranks. Here is an example output for this section:
----------
The third section above lists the number of owned atoms (Nlocal),
ghost atoms (Nghost), and pair-wise neighbors stored per processor.
ghost atoms (Nghost), and pairwise neighbors stored per processor.
The max and min values give the spread of these values across
processors with a 10-bin histogram showing the distribution. The total
number of histogram counts is equal to the number of processors.
@ -114,7 +114,7 @@ number of histogram counts is equal to the number of processors.
----------
The last section gives aggregate statistics (across all processors)
for pair-wise neighbors and special neighbors that LAMMPS keeps track
for pairwise neighbors and special neighbors that LAMMPS keeps track
of (see the :doc:`special_bonds <special_bonds>` command). The number
of times neighbor lists were rebuilt is tallied, as is the number of
potentially *dangerous* rebuilds. If atom movement triggered neighbor

2
doc/src/Speed_kokkos.rst
View File

@ -214,7 +214,7 @@ threads/task as Nt. The product of these two values should be N, i.e.
The default for the :doc:`package kokkos <package>` command when
running on KNL is to use "half" neighbor lists and set the Newton flag
to "on" for both pairwise and bonded interactions. This will typically
be best for many-body potentials. For simpler pair-wise potentials, it
be best for many-body potentials. For simpler pairwise potentials, it
may be faster to use a "full" neighbor list with Newton flag to "off".
Use the "-pk kokkos" :doc:`command-line switch <Run_options>` to change
the default :doc:`package kokkos <package>` options. See its page for

29
doc/src/Tools.rst
View File

@ -277,17 +277,34 @@ at ens-lyon.fr, alain.dequidt at uca.fr
eam database tool
-----------------------------
The tools/eam_database directory contains a Fortran program that will
generate EAM alloy setfl potential files for any combination of 16
elements: Cu, Ag, Au, Ni, Pd, Pt, Al, Pb, Fe, Mo, Ta, W, Mg, Co, Ti,
Zr. The files can then be used with the :doc:`pair_style eam/alloy <pair_eam>` command.
The tools/eam_database directory contains a Fortran and a Python program
that will generate EAM alloy setfl potential files for any combination
of the 17 elements: Cu, Ag, Au, Ni, Pd, Pt, Al, Pb, Fe, Mo, Ta, W, Mg,
Co, Ti, Zr, Cr. The files can then be used with the :doc:`pair_style
eam/alloy <pair_eam>` command.
The tool is authored by Xiaowang Zhou (Sandia), xzhou at sandia.gov,
and is based on his paper:
The Fortran version of the tool was authored by Xiaowang Zhou (Sandia),
xzhou at sandia.gov, with updates from Lucas Hale (NIST) lucas.hale at
nist.gov and is based on his paper:
X. W. Zhou, R. A. Johnson, and H. N. G. Wadley, Phys. Rev. B, 69,
144113 (2004).
The parameters for Cr were taken from:
Lin Z B, Johnson R A and Zhigilei L V, Phys. Rev. B 77 214108 (2008).
The Python version of the tool was authored by Germain Clavier
(TU Eindhoven) g.m.g.c.clavier at tue.nl or germain.clavier at gmail.com
.. note::
The parameters in the database are only optimized for individual
elements. The mixed parameters for interactions between different
elements generated by this tool are derived from simple mixing rules
and are thus inferior to parameterizations that are specifically
optimized for specific mixtures and combinations of elements.
----------
.. _eamgn:

38
doc/src/angle_class2.rst
View File

@ -64,34 +64,44 @@ These are the 4 coefficients for the :math:`E_a` formula:
radians internally; hence the various :math:`K` are effectively energy
per radian\^2 or radian\^3 or radian\^4.
For the :math:`E_{bb}` formula, each line in a :doc:`angle_coeff <angle_coeff>`
command in the input script lists 4 coefficients, the first of which
is "bb" to indicate they are BondBond coefficients. In a data file,
these coefficients should be listed under a "BondBond Coeffs" heading
and you must leave out the "bb", i.e. only list 3 coefficients after
the angle type.
For the :math:`E_{bb}` formula, each line in a :doc:`angle_coeff
<angle_coeff>` command in the input script lists 4 coefficients, the
first of which is "bb" to indicate they are BondBond coefficients. In
a data file, these coefficients should be listed under a "BondBond
Coeffs" heading and you must leave out the "bb", i.e. only list 3
coefficients after the angle type.
* bb
* :math:`M` (energy/distance\^2)
* :math:`r_1` (distance)
* :math:`r_2` (distance)
For the :math:`E_{ba}` formula, each line in a :doc:`angle_coeff <angle_coeff>`
command in the input script lists 5 coefficients, the first of which
is "ba" to indicate they are BondAngle coefficients. In a data file,
these coefficients should be listed under a "BondAngle Coeffs" heading
and you must leave out the "ba", i.e. only list 4 coefficients after
the angle type.
For the :math:`E_{ba}` formula, each line in a :doc:`angle_coeff
<angle_coeff>` command in the input script lists 5 coefficients, the
first of which is "ba" to indicate they are BondAngle coefficients.
In a data file, these coefficients should be listed under a "BondAngle
Coeffs" heading and you must leave out the "ba", i.e. only list 4
coefficients after the angle type.
* ba
* :math:`N_1` (energy/distance\^2)
* :math:`N_2` (energy/distance\^2)
* :math:`N_1` (energy/distance)
* :math:`N_2` (energy/distance)
* :math:`r_1` (distance)
* :math:`r_2` (distance)
The :math:`\theta_0` value in the :math:`E_{ba}` formula is not specified,
since it is the same value from the :math:`E_a` formula.
.. note::
It is important that the order of the I,J,K atoms in each angle
listed in the Angles section of the data file read by the
:doc:`read_data <read_data>` command be consistent with the order
of the :math:`r_1` and :math:`r_2` BondBond and BondAngle
coefficients. This is because the terms in the formulas for
:math:`E_{bb}` and :math:`E_{ba}` will use the I,J atoms to compute
:math:`r_{ij}` and the J,K atoms to compute :math:`r_{jk}`.
----------
.. include:: accel_styles.rst

2
doc/src/balance.rst
View File

@ -383,7 +383,7 @@ multiple groups, its weight is the product of the weight factors.
This weight style is useful in combination with pair style
:doc:`hybrid <pair_hybrid>`, e.g. when combining a more costly many-body
potential with a fast pair-wise potential. It is also useful when
potential with a fast pairwise potential. It is also useful when
using :doc:`run_style respa <run_style>` where some portions of the
system have many bonded interactions and others none. It assumes that
the computational cost for each group remains constant over time.

46
doc/src/bond_fene.rst
View File

@ -1,4 +1,5 @@
.. index:: bond_style fene
.. index:: bond_style fene/nm
.. index:: bond_style fene/intel
.. index:: bond_style fene/kk
.. index:: bond_style fene/omp
@ -8,12 +9,16 @@ bond_style fene command
Accelerator Variants: *fene/intel*, *fene/kk*, *fene/omp*
bond_style fene/nm command
==========================
Syntax
""""""
.. code-block:: LAMMPS
bond_style fene
bond_style fene/nm
Examples
""""""""
@ -23,6 +28,9 @@ Examples
bond_style fene
bond_coeff 1 30.0 1.5 1.0 1.0
bond_style fene/nm
bond_coeff 1 2.25344 1.5 1.0 1.12246 2 6
Description
"""""""""""
@ -38,16 +46,36 @@ term is attractive, the second Lennard-Jones term is repulsive. The
first term extends to :math:`R_0`, the maximum extent of the bond. The second
term is cutoff at :math:`2^\frac{1}{6} \sigma`, the minimum of the LJ potential.
The following coefficients must be defined for each bond type via the
:doc:`bond_coeff <bond_coeff>` command as in the example above, or in
the data file or restart files read by the :doc:`read_data <read_data>`
or :doc:`read_restart <read_restart>` commands:
The *fene/nm* bond style substitutes the standard LJ potential with the generalized LJ potential
in the same form as in pair style :doc:`nm/cut <pair_nm>`. The bond energy is then given by
.. math::
E = -0.5 K r_0^2 \ln \left[ 1 - \left(\frac{r}{R_0}\right)^2\right] + \frac{E_0}{(n-m)} \left[ m \left(\frac{r_0}{r}\right)^n - n \left(\frac{r_0}{r}\right)^m \right]
Similar to the *fene* style, the generalized Lennard-Jones is cut off at
the potential minimum, :math:`r_0`, to be repulsive only. The following
coefficients must be defined for each bond type via the :doc:`bond_coeff
<bond_coeff>` command as in the example above, or in the data file or
restart files read by the :doc:`read_data <read_data>` or
:doc:`read_restart <read_restart>` commands:
* :math:`K` (energy/distance\^2)
* :math:`R_0` (distance)
* :math:`\epsilon` (energy)
* :math:`\sigma` (distance)
For the *fene/nm* style, the following coefficients are used. Please
note, that the standard LJ potential and thus the regular FENE potential
is recovered for (n=12 m=6) and :math:`r_0 = 2^\frac{1}{6} \sigma`.
* :math:`K` (energy/distance\^2)
* :math:`R_0` (distance)
* :math:`E_0` (energy)
* :math:`r_0` (distance)
* :math:`n` (unitless)
* :math:`m` (unitless)
----------
.. include:: accel_styles.rst
@ -57,9 +85,10 @@ or :doc:`read_restart <read_restart>` commands:
Restrictions
""""""""""""
This bond style can only be used if LAMMPS was built with the MOLECULE
package. See the :doc:`Build package <Build_package>` page for more
info.
The *fene* bond style can only be used if LAMMPS was built with the MOLECULE
package; the *fene/nm* bond style can only be used if LAMMPS was built
with the EXTRA-MOLECULE package. See the :doc:`Build package <Build_package>`
page for more info.
You typically should specify :doc:`special_bonds fene <special_bonds>`
or :doc:`special_bonds lj/coul 0 1 1 <special_bonds>` to use this bond
@ -68,7 +97,8 @@ style. LAMMPS will issue a warning it that's not the case.
Related commands
""""""""""""""""
:doc:`bond_coeff <bond_coeff>`, :doc:`delete_bonds <delete_bonds>`
:doc:`bond_coeff <bond_coeff>`, :doc:`delete_bonds <delete_bonds>`,
:doc:`pair style lj/cut <pair_lj>`, :doc:`pair style nm/cut <pair_nm>`.
Default
"""""""

1
doc/src/bond_style.rst
View File

@ -87,6 +87,7 @@ accelerated styles exist.
* :doc:`class2 <bond_class2>` - COMPASS (class 2) bond
* :doc:`fene <bond_fene>` - FENE (finite-extensible non-linear elastic) bond
* :doc:`fene/expand <bond_fene_expand>` - FENE bonds with variable size particles
* :doc:`fene/nm <bond_fene>` - FENE bonds with a generalized Lennard-Jones potential
* :doc:`gaussian <bond_gaussian>` - multicentered Gaussian-based bond potential
* :doc:`gromos <bond_gromos>` - GROMOS force field bond
* :doc:`harmonic <bond_harmonic>` - harmonic bond

5
doc/src/compute.rst
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@ -174,6 +174,7 @@ The individual style names on the :doc:`Commands compute <Commands_compute>` pag
* :doc:`angle <compute_angle>` - energy of each angle sub-style
* :doc:`angle/local <compute_angle_local>` - theta and energy of each angle
* :doc:`angmom/chunk <compute_angmom_chunk>` - angular momentum for each chunk
* :doc:`ave/sphere/atom <compute_ave_sphere_atom>` - compute local density and temperature around each atom
* :doc:`basal/atom <compute_basal_atom>` - calculates the hexagonal close-packed "c" lattice vector of each atom
* :doc:`body/local <compute_body_local>` - attributes of body sub-particles
* :doc:`bond <compute_bond>` - energy of each bond sub-style
@ -245,7 +246,6 @@ The individual style names on the :doc:`Commands compute <Commands_compute>` pag
* :doc:`pe/tally <compute_tally>` - potential energy between two groups of atoms via the tally callback mechanism
* :doc:`plasticity/atom <compute_plasticity_atom>` - Peridynamic plasticity for each atom
* :doc:`pressure <compute_pressure>` - total pressure and pressure tensor
* :doc:`pressure/cylinder <compute_pressure_cylinder>` - pressure tensor in cylindrical coordinates
* :doc:`pressure/uef <compute_pressure_uef>` - pressure tensor in the reference frame of an applied flow field
* :doc:`property/atom <compute_property_atom>` - convert atom attributes to per-atom vectors/arrays
* :doc:`property/chunk <compute_property_chunk>` - extract various per-chunk attributes
@ -288,8 +288,11 @@ The individual style names on the :doc:`Commands compute <Commands_compute>` pag
* :doc:`sph/t/atom <compute_sph_t_atom>` - per-atom internal temperature of Smooth-Particle Hydrodynamics atoms
* :doc:`spin <compute_spin>` - magnetic quantities for a system of atoms having spins
* :doc:`stress/atom <compute_stress_atom>` - stress tensor for each atom
* :doc:`stress/cartesian <compute_stress_profile>` - stress tensor in cartesian coordinates
* :doc:`stress/cylinder <compute_stress_profile>` - stress tensor in cylindrical coordinates
* :doc:`stress/mop <compute_stress_mop>` - normal components of the local stress tensor using the method of planes
* :doc:`stress/mop/profile <compute_stress_mop>` - profile of the normal components of the local stress tensor using the method of planes
* :doc:`stress/spherical <compute_stress_profile>` - stress tensor in spherical coordinates
* :doc:`stress/tally <compute_tally>` - stress between two groups of atoms via the tally callback mechanism
* :doc:`tdpd/cc/atom <compute_tdpd_cc_atom>` - per-atom chemical concentration of a specified species for each tDPD particle
* :doc:`temp <compute_temp>` - temperature of group of atoms

101
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@ -0,0 +1,101 @@
.. index:: compute ave/sphere/atom
.. index:: compute ave/sphere/atom/kk
compute ave/sphere/atom command
================================
Accelerator Variants: *ave/sphere/atom/kk*
Syntax
""""""
.. parsed-literal::
compute ID group-ID ave/sphere/atom keyword values ...
* ID, group-ID are documented in :doc:`compute <compute>` command
* ave/sphere/atom = style name of this compute command
* one or more keyword/value pairs may be appended
.. parsed-literal::
keyword = *cutoff*
*cutoff* value = distance cutoff
Examples
""""""""
.. code-block:: LAMMPS
compute 1 all ave/sphere/atom
compute 1 all ave/sphere/atom cutoff 5.0
comm_modify cutoff 5.0
Description
"""""""""""
Define a computation that calculates the local density and temperature
for each atom and neighbors inside a spherical cutoff.
The optional keyword *cutoff* defines the distance cutoff
used when searching for neighbors. The default value is the cutoff
specified by the pair style. If no pair style is defined, then a cutoff
must be defined using this keyword. If the specified cutoff is larger than
that of the pair_style plus neighbor skin (or no pair style is defined),
the *comm_modify cutoff* option must also be set to match that of the
*cutoff* keyword.
The neighbor list needed to compute this quantity is constructed each
time the calculation is performed (i.e. each time a snapshot of atoms
is dumped). Thus it can be inefficient to compute/dump this quantity
too frequently.
.. note::
If you have a bonded system, then the settings of
:doc:`special_bonds <special_bonds>` command can remove pairwise
interactions between atoms in the same bond, angle, or dihedral. This
is the default setting for the :doc:`special_bonds <special_bonds>`
command, and means those pairwise interactions do not appear in the
neighbor list. Because this fix uses the neighbor list, it also means
those pairs will not be included in the order parameter. This
difficulty can be circumvented by writing a dump file, and using the
:doc:`rerun <rerun>` command to compute the order parameter for
snapshots in the dump file. The rerun script can use a
:doc:`special_bonds <special_bonds>` command that includes all pairs in
the neighbor list.
----------
.. include:: accel_styles.rst
----------
Output info
"""""""""""
This compute calculates a per-atom array with two columns: density and temperature.
These values can be accessed by any command that uses per-atom values
from a compute as input. See the :doc:`Howto output <Howto_output>` doc
page for an overview of LAMMPS output options.
Restrictions
""""""""""""
This compute is part of the EXTRA-COMPUTE package. It is only enabled if
LAMMPS was built with that package. See the :doc:`Build package <Build_package>` page for more info.
Related commands
""""""""""""""""
:doc:`comm_modify <comm_modify>`
Default
"""""""
The option defaults are *cutoff* = pair style cutoff

21
doc/src/compute_heat_flux.rst
View File

@ -89,13 +89,20 @@ included in the calculation.
.. warning::
The compute *heat/flux* has been reported to produce unphysical
values for angle, dihedral and improper contributions
values for angle, dihedral, improper and constraint force contributions
when used with :doc:`compute stress/atom <compute_stress_atom>`,
as discussed in :ref:`(Surblys) <Surblys2>` and :ref:`(Boone) <Boone>`.
You are strongly advised to
as discussed in :ref:`(Surblys2019) <Surblys3>`, :ref:`(Boone) <Boone>`
and :ref:`(Surblys2021) <Surblys4>`. You are strongly advised to
use :doc:`compute centroid/stress/atom <compute_stress_atom>`,
which has been implemented specifically for such cases.
.. warning::
Due to an implementation detail, the :math:`y` and :math:`z`
components of heat flux from :doc:`fix rigid <fix_rigid>`
contribution when computed via :doc:`compute stress/atom <compute_stress_atom>`
are highly unphysical and should not be used.
The Green-Kubo formulas relate the ensemble average of the
auto-correlation of the heat flux :math:`\mathbf{J}`
to the thermal conductivity :math:`\kappa`:
@ -232,10 +239,14 @@ none
----------
.. _Surblys2:
.. _Surblys3:
**(Surblys)** Surblys, Matsubara, Kikugawa, Ohara, Phys Rev E, 99, 051301(R) (2019).
**(Surblys2019)** Surblys, Matsubara, Kikugawa, Ohara, Phys Rev E, 99, 051301(R) (2019).
.. _Boone:
**(Boone)** Boone, Babaei, Wilmer, J Chem Theory Comput, 15, 5579--5587 (2019).
.. _Surblys4:
**(Surblys2021)** Surblys, Matsubara, Kikugawa, Ohara, J Appl Phys 130, 215104 (2021).

9
doc/src/compute_momentum.rst
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@ -23,11 +23,10 @@ Examples
Description
"""""""""""
Define a computation that calculates the translational momentum
of a group of particles.
The momentum of each particles is computed as m v, where m and v are
the mass and velocity of the particle.
Define a computation that calculates the translational momentum *p*
of a group of particles. It is computed as the sum :math:`\vec{p} = \sum_i m_i \cdot \vec{v}_i`
over all particles in the compute group, where *m* and *v* are
the mass and velocity vector of the particle, respectively.
Output info
"""""""""""

2
doc/src/compute_pressure.rst
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@ -141,7 +141,7 @@ Related commands
""""""""""""""""
:doc:`compute temp <compute_temp>`, :doc:`compute stress/atom <compute_stress_atom>`,
:doc:`thermo_style <thermo_style>`,
:doc:`thermo_style <thermo_style>`, :doc:`fix numdiff/virial <fix_numdiff_virial>`,
Default
"""""""

88
doc/src/compute_pressure_cylinder.rst
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@ -1,88 +0,0 @@
.. index:: compute pressure/cylinder
compute pressure/cylinder command
=================================
Syntax
""""""
.. parsed-literal::
compute ID group-ID pressure/cylinder zlo zhi Rmax bin_width
* ID, group-ID are documented in :doc:`compute <compute>` command
* pressure/cylinder = style name of this compute command
* zlo = minimum z-boundary for cylinder
* zhi = maximum z-boundary for cylinder
* Rmax = maximum radius to perform calculation to
* bin_width = width of radial bins to use for calculation
Examples
""""""""
.. code-block:: LAMMPS
compute 1 all pressure/cylinder -10.0 10.0 15.0 0.25
Description
"""""""""""
Define a computation that calculates the pressure tensor of a system in
cylindrical coordinates, as discussed in :ref:`(Addington) <Addington1>`.
This is useful for systems with a single axis of rotational symmetry,
such as cylindrical micelles or carbon nanotubes. The compute splits the
system into radial, cylindrical-shell-type bins of width bin_width,
centered at x=0,y=0, and calculates the radial (P_rhorho), azimuthal
(P_phiphi), and axial (P_zz) components of the configurational pressure
tensor. The local density is also calculated for each bin, so that the
true pressure can be recovered as P_kin+P_conf=density\*k\*T+P_conf. The
output is a global array with 5 columns; one each for bin radius, local
number density, P_rhorho, P_phiphi, and P_zz. The number of rows is
governed by the values of Rmax and bin_width. Pressure tensor values are
output in pressure units.
Output info
"""""""""""
This compute calculates a global array with 5 columns and Rmax/bin_width
rows. The output columns are: R (distance units), number density (inverse
volume units), configurational radial pressure (pressure units),
configurational azimuthal pressure (pressure units), and configurational
axial pressure (pressure units).
The values calculated by this compute are
"intensive". The pressure values will be in pressure
:doc:`units <units>`. The number density values will be in
inverse volume :doc:`units <units>`.
Restrictions
""""""""""""
This compute currently calculates the pressure tensor contributions
for pair styles only (i.e. no bond, angle, dihedral, etc. contributions
and in the presence of bonded interactions, the result will be incorrect
due to exclusions for special bonds) and requires pair-wise force
calculations not available for most many-body pair styles. K-space
calculations are also excluded. Note that this pressure compute outputs
the configurational terms only; the kinetic contribution is not included
and may be calculated from the number density output by P_kin=density\*k\*T.
This compute is part of the EXTRA-COMPUTE package. It is only enabled
if LAMMPS was built with that package. See the :doc:`Build package <Build_package>` page for more info.
Related commands
""""""""""""""""
:doc:`compute temp <compute_temp>`, :doc:`compute stress/atom <compute_stress_atom>`,
:doc:`thermo_style <thermo_style>`,
Default
"""""""
none
----------
.. _Addington1:
**(Addington)** Addington, Long, Gubbins, J Chem Phys, 149, 084109 (2018).

38
doc/src/compute_sna_atom.rst
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@ -33,7 +33,7 @@ Syntax
* R_1, R_2,... = list of cutoff radii, one for each type (distance units)
* w_1, w_2,... = list of neighbor weights, one for each type
* zero or more keyword/value pairs may be appended
* keyword = *rmin0* or *switchflag* or *bzeroflag* or *quadraticflag* or *chem* or *bnormflag* or *wselfallflag*
* keyword = *rmin0* or *switchflag* or *bzeroflag* or *quadraticflag* or *chem* or *bnormflag* or *wselfallflag* or *bikflag* or *switchinnerflag*
.. parsed-literal::
@ -56,6 +56,12 @@ Syntax
*wselfallflag* value = *0* or *1*
*0* = self-contribution only for element of central atom
*1* = self-contribution for all elements
*bikflag* value = *0* or *1* (only implemented for compute snap)
*0* = per-atom bispectrum descriptors are summed over atoms
*1* = per-atom bispectrum descriptors are not summed over atoms
*switchinnerflag* values = *rinnerlist* *drinnerlist*
*rinnerlist* = *ntypes* values of rinner (distance units)
*drinnerlist* = *ntypes* values of drinner (distance units)
Examples
""""""""
@ -67,6 +73,7 @@ Examples
compute vb all sna/atom 1.4 0.95 6 2.0 1.0
compute snap all snap 1.4 0.95 6 2.0 1.0
compute snap all snap 1.0 0.99363 6 3.81 3.83 1.0 0.93 chem 2 0 1
compute snap all snap 1.0 0.99363 6 3.81 3.83 1.0 0.93 switchinnerflag 1.1 1.3 0.5 0.6
Description
"""""""""""
@ -296,6 +303,35 @@ This option is typically used in conjunction with the *chem* keyword,
and LAMMPS will generate a warning if both *chem* and *bnormflag*
are not both set or not both unset.
The keyword *bikflag* determines whether or not to expand the bispectrum
rows of the global array returned by compute snap. If *bikflag* is set
to *1* then the bispectrum row, which is typically the per-atom bispectrum
descriptors :math:`B_{i,k}` summed over all atoms *i* to produce
:math:`B_k`, becomes bispectrum rows equal to the number of atoms. Thus,
the resulting bispectrum rows are :math:`B_{i,k}` instead of just
:math:`B_k`. In this case, the entries in the final column for these rows
are set to zero.
The keyword *switchinnerflag* activates an additional radial switching
function similar to :math:`f_c(r)` above, but acting to switch off
smoothly contributions from neighbor atoms at short separation distances.
This is useful when SNAP is used in combination with a simple
repulsive potential. The keyword is followed by the *ntypes*
values for :math:`r_{inner}` and the *ntypes*
values for :math:`\Delta r_{inner}`. For a neighbor atom at
distance :math:`r`, its contribution is scaled by a multiplicative
factor :math:`f_{inner}(r)` defined as follows:
.. math::
= & 0, r \leq r_{inner} \\
f_{inner}(r) = & \frac{1}{2}(1 - \cos(\pi \frac{r-r_{inner}}{\Delta r_{inner}})), r_{inner} < r \leq r_{inner} + \Delta r_{inner} \\
= & 1, r > r_{inner} + \Delta r_{inner}
The values of :math:`r_{inner}` and :math:`\Delta r_{inner}` are
the arithmetic means of the values for the central atom of type I
and the neighbor atom of type J.
.. note::
If you have a bonded system, then the settings of :doc:`special_bonds

45
doc/src/compute_stress_atom.rst
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@ -87,6 +87,10 @@ Tersoff 3-body interaction) is assigned in equal portions to each atom
in the set. E.g. 1/4 of the dihedral virial to each of the 4 atoms,
or 1/3 of the fix virial due to SHAKE constraints applied to atoms in
a water molecule via the :doc:`fix shake <fix_shake>` command.
As an exception, the virial contribution from
constraint forces in :doc:`fix rigid <fix_rigid>` on each atom
is computed from the constraint force acting on the corresponding atom
and its position, i.e. the total virial is not equally distributed.
In case of compute *centroid/stress/atom*, the virial contribution is:
@ -103,13 +107,25 @@ atom :math:`I` due to the interaction and the relative position
:math:`\mathbf{r}_{I0}` of the atom :math:`I` to the geometric center
of the interacting atoms, i.e. centroid, is used. As the geometric
center is different for each interaction, the :math:`\mathbf{r}_{I0}`
also differs. The sixth and seventh terms, Kspace and :doc:`fix
<fix>` contribution respectively, are computed identical to compute
*stress/atom*. Although the total system virial is the same as
also differs. The sixth term, Kspace contribution,
is computed identically to compute *stress/atom*.
The seventh term is handed differently depending on
if the constraint forces are due to :doc:`fix shake <fix_shake>`
or :doc:`fix rigid <fix_rigid>`.
In case of SHAKE constraints, each distance constraint is
handed as a pairwise interaction.
E.g. in case of a water molecule, two OH and one HH distance
constraints are treated as three pairwise interactions.
In case of :doc:`fix rigid <fix_rigid>`,
all constraint forces in the molecule are treated
as a single many-body interaction with a single centroid position.
In case of water molecule, the formula expression would become
identical to that of the three-body angle interaction.
Although the total system virial is the same as
compute *stress/atom*, compute *centroid/stress/atom* is know to
result in more consistent heat flux values for angle, dihedrals and
improper contributions when computed via :doc:`compute heat/flux
<compute_heat_flux>`.
result in more consistent heat flux values for angle, dihedrals,
improper and constraint force contributions
when computed via :doc:`compute heat/flux <compute_heat_flux>`.
If no extra keywords are listed, the kinetic contribution all of the
virial contribution terms are included in the per-atom stress tensor.
@ -134,7 +150,8 @@ contribution for the cluster interaction is divided evenly among those
atoms.
Details of how compute *centroid/stress/atom* obtains the virial for
individual atoms is given in :ref:`(Surblys) <Surblys1>`, where the
individual atoms are given in :ref:`(Surblys2019) <Surblys1>` and
:ref:`(Surblys2021) <Surblys2>`, where the
idea is that the virial of the atom :math:`I` is the result of only
the force :math:`\mathbf{F}_I` on the atom due to the interaction and
its positional vector :math:`\mathbf{r}_{I0}`, relative to the
@ -235,10 +252,10 @@ between the pair of particles. All bond styles are supported. All
angle, dihedral, improper styles are supported with the exception of
INTEL and KOKKOS variants of specific styles. It also does not
support models with long-range Coulombic or dispersion forces,
i.e. the kspace_style command in LAMMPS. It also does not support the
following fixes which add rigid-body constraints: :doc:`fix shake
<fix_shake>`, :doc:`fix rattle <fix_shake>`, :doc:`fix rigid
<fix_rigid>`, :doc:`fix rigid/small <fix_rigid>`.
i.e. the kspace_style command in LAMMPS. It also does not implement the
following fixes which add rigid-body constraints:
:doc:`fix rigid/* <fix_rigid>` and the OpenMP accelerated version of :doc:`fix rigid/small <fix_rigid>`,
while all other :doc:`fix rigid/*/small <fix_rigid>` are implemented.
LAMMPS will generate an error if one of these options is included in
your model. Extension of centroid stress calculations to these force
@ -270,4 +287,8 @@ none
.. _Surblys1:
**(Surblys)** Surblys, Matsubara, Kikugawa, Ohara, Phys Rev E, 99, 051301(R) (2019).
**(Surblys2019)** Surblys, Matsubara, Kikugawa, Ohara, Phys Rev E, 99, 051301(R) (2019).
.. _Surblys2:
**(Surblys2021)** Surblys, Matsubara, Kikugawa, Ohara, J Appl Phys 130, 215104 (2021).

25
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@ -68,7 +68,19 @@ configurational stress (conf), and/or total stress (total).
NOTE 1: The configurational stress is computed considering all pairs of atoms where at least one atom belongs to group group-ID.
NOTE 2: The local stress does not include any Lennard-Jones tail
corrections to the pressure added by the :doc:`pair_modify tail yes <pair_modify>` command, since those are contributions to the global system pressure.
corrections to the stress added by the :doc:`pair_modify tail yes <pair_modify>`
command, since those are contributions to the global system pressure.
NOTE 3: The local stress profile generated by compute *stress/mop/profile*
is similar to that obtained by compute
:doc:`stress/cartesian <compute_stress_profile>`.
A key difference
is that compute *stress/mop/profile* considers particles
crossing a set of planes,
while compute *stress/cartesian* computes averages for a set of
small volumes. More information
on the similarities and differences can be found in
:ref:`(Ikeshoji)<Ikeshoji2>`.
Output info
"""""""""""
@ -87,7 +99,10 @@ and stress_dir,z.
The values are in pressure :doc:`units <units>`.
The values produced by this compute can be accessed by various :doc:`output commands <Howto_output>`. For instance, the results can be written to a file using the :doc:`fix ave/time <fix_ave_time>` command. Please see the example in the examples/PACKAGES/mop folder.
The values produced by this compute can be accessed by various :doc:`output commands <Howto_output>`.
For instance, the results can be written to a file using the
:doc:`fix ave/time <fix_ave_time>` command. Please see the example
in the examples/PACKAGES/mop folder.
Restrictions
""""""""""""
@ -107,7 +122,7 @@ intra-molecular interactions, and long range (kspace) interactions.
Related commands
""""""""""""""""
:doc:`compute stress/atom <compute_stress_atom>`
:doc:`compute stress/atom <compute_stress_atom>`, :doc:`compute pressure <compute_pressure>`, :doc:`compute stress/cartesian <compute_stress_profile>`, :doc:`compute stress/cylinder <compute_stress_profile>`, :doc:`compute stress/spherical <compute_stress_profile>`
Default
"""""""
@ -120,3 +135,7 @@ none
**(Todd)** B. D. Todd, Denis J. Evans, and Peter J. Daivis: "Pressure tensor for inhomogeneous fluids",
Phys. Rev. E 52, 1627 (1995).
.. _Ikeshoji3:
**(Ikeshoji)** Ikeshoji, Hafskjold, Furuholt, Mol Sim, 29, 101-109, (2003).

165
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@ -0,0 +1,165 @@
.. index:: compute stress/cartesian
.. index:: compute stress/cylinder
.. index:: compute stress/spherical
compute stress/cartesian command
==================================
compute stress/cylinder command
=================================
compute stress/spherical command
==================================
Syntax
""""""
.. parsed-literal::
compute ID group-ID style args
* ID, group-ID are documented in :doc:`compute <compute>` command
* style = stress/cartesian or stress/spherical or stress/cylinder
* args = argument specific to the compute style
.. parsed-literal::
*stress/cartesian* args = dim bin_width
dim = x, y, or z. One or two dim/bin_width pairs may be appended
bin_width = width of the bin
*stress/cylinder* args = zlo zh Rmax bin_width keyword
zlo = minimum z-boundary for cylinder
zhi = maximum z-boundary for cylinder
Rmax = maximum radius to perform calculation to
bin_width = width of radial bins to use for calculation
keyword = ke (zero or one can be specified)
ke = yes or no
*stress/spherical*
x0, y0, z0 = origin of the spherical coordinate system
bin_width = width of spherical shells
Rmax = maximum radius of spherical shells
Examples
""""""""
.. code-block:: LAMMPS
compute 1 all stress/cartesian x 0.1
compute 1 all stress/cartesian y 0.25 z 0.1
compute 1 all stress/cylinder -10.0 10.0 15.0 0.25
compute 1 all stress/cylinder -10.0 10.0 15.0 0.25 ke no
compute 1 all stress/spherical 0 0 0 0.1 10
Description
"""""""""""
Compute *stress/cartesian*, compute *stress/cylinder*, and compute
*stress/spherical* define computations that calculate profiles of the
diagonal components of the local stress tensor in the specified
coordinate system. The stress tensor is split into a kinetic
contribution :math:`P^k` and a virial contribution :math:`P^v`. The sum
gives the total stress tensor :math:`P = P^k+P^v`. These computes can
for example be used to calculate the diagonal components of the local
stress tensor of interfaces with flat, cylindrical, or spherical
symmetry. These computes obeys momentum balance through fluid
interfaces. They use the Irving-Kirkwood contour, which is the straight
line between particle pairs.
The *stress/cartesian* computes the stress profile along one or two
Cartesian coordinates, as described in :ref:`(Ikeshoji)<Ikeshoji2>`. The
compute *stress/cylinder* computes the stress profile along the
radial direction in cylindrical coordinates, as described in
:ref:`(Addington)<Addington1>`. The compute *stress/spherical*
computes the stress profile along the radial direction in spherical
coordinates, as described in :ref:`(Ikeshoji)<Ikeshoji2>`.
Output info
"""""""""""
The output columns for *stress/cartesian* are the position of the
center of the local volume in the first and second dimensions, number
density, :math:`P^k_{xx}`, :math:`P^k_{yy}`, :math:`P^k_{zz}`,
:math:`P^v_{xx}`, :math:`P^v_{yy}`, and :math:`P^v_{zz}`. There are 8
columns when one dimension is specified and 9 columns when two
dimensions are specified. The number of bins/rows are
(L1/bin_width1)*(L2/bin_width2), L1 and L2 are the sizes of the
simulation box in the specified dimensions, and bin_width1 and
bin_width2 are the specified bin widths. When only one dimension is
specified the number of bins/rows are L1/bin_width.
The default output columns for *stress/cylinder* are the radius to the
center of the cylindrical shell, number density, :math:`P^k_{rr}`,
:math:`P^k_{\phi\phi}`, :math:`P^k_{zz}`, :math:`P^v_{rr}`,
:math:`P^v_{\phi\phi}`, and :math:`P^v_{zz}`. When the keyword *ke* is
set to no, the kinetic contributions are not calculated, and
consequently there are only 5 columns the radius to the center of the
cylindrical shell, number density, :math:`P^v_{rr}`,
:math:`P^v_{\phi\phi}`, :math:`P^v_{zz}`. The number of bins/rows are
Rmax/bin_width.
The output columns for *stress/spherical* are the radius to the center
of the spherical shell, number density, :math:`P^k_{rr}`,
:math:`P^k_{\theta\theta}`, :math:`P^k_{\phi\phi}`, :math:`P^v_{rr}`,
:math:`P^v_{\theta\theta}`, and :math:`P^v_{\phi\phi}`. There are 8
columns and the number of bins/rows are Rmax/bin_width.
This array can be output with :doc:`fix ave/time <fix_ave_time>`,
.. code-block:: LAMMPS
compute p all stress/cartesian x 0.1
fix 2 all ave/time 100 1 100 c_p[*] file dump_p.out mode vector
The values calculated by this compute are "intensive". The stress
values will be in pressure :doc:`units <units>`. The number density
values are in inverse volume :doc:`units <units>`.
NOTE 1: The local stress does not include any Lennard-Jones tail
corrections to the stress added by the :doc:`pair_modify tail yes <pair_modify>`
command, since those are contributions to the global system pressure.
NOTE 2: The local stress profiles generated by these computes are
similar to those obtained by the
:doc:`method-of-planes (MOP) <compute_stress_mop>`.
A key difference
is that compute `stress/mop/profile <compute_stress_mop>`
considers particles crossing a set of planes, while
*stress/cartesian* computes averages for a set of small volumes.
More information on the similarities and differences can be found in
:ref:`(Ikeshoji)<Ikeshoji2>`.
Restrictions
""""""""""""
These computes calculate the stress tensor contributions for pair
styles only (i.e. no bond, angle, dihedral, etc. contributions, and in
the presence of bonded interactions, the result will be incorrect due to
exclusions for special bonds) and requires pairwise force calculations
not available for most many-body pair styles. K-space calculations are
also excluded.
These computes are part of the EXTRA-COMPUTE package. They are only
enabled if LAMMPS was built with that package. See the :doc:`Build
package <Build_package>` doc page for more info.
Related commands
""""""""""""""""
:doc:`compute stress/atom <compute_stress_atom>`, :doc:`compute pressure <compute_pressure>`, :doc:`compute stress/mop/profile <compute_stress_mop>`
Default
"""""""
The keyword default for ke in style *stress/cylinder* is yes.
----------
.. _Ikeshoji2:
**(Ikeshoji)** Ikeshoji, Hafskjold, Furuholt, Mol Sim, 29, 101-109, (2003).
.. _Addington1:
**(Addington)** Addington, Long, Gubbins, J Chem Phys, 149, 084109 (2018).

30
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View File

@ -31,7 +31,7 @@ Syntax
compute ID group-ID style group2-ID
* ID, group-ID are documented in :doc:`compute <compute>` command
* style = *force/tally* or *heat/flux/tally* or *heat/flux/virial/tally* or * or *pe/tally* or *pe/mol/tally* or *stress/tally*
* style = *force/tally* or *heat/flux/tally* or *heat/flux/virial/tally* or *pe/tally* or *pe/mol/tally* or *stress/tally*
* group2-ID = group ID of second (or same) group
Examples
@ -61,7 +61,7 @@ mechanism. Compute *pe/mol/tally* is one such style, that can
- through using this mechanism - separately tally intermolecular
and intramolecular energies. Something that would otherwise be
impossible without integrating this as a core functionality into
the based classes of LAMMPS.
the base classes of LAMMPS.
----------
@ -148,27 +148,35 @@ pairwise property computations.
Output info
"""""""""""
Compute *pe/tally* calculates a global scalar (the energy) and a per
- Compute *pe/tally* calculates a global scalar (the energy) and a per
atom scalar (the contributions of the single atom to the global
scalar). Compute *pe/mol/tally* calculates a global 4-element vector
containing (in this order): *evdwl* and *ecoul* for intramolecular pairs
and *evdwl* and *ecoul* for intermolecular pairs. Since molecules are
scalar).
- Compute *pe/mol/tally* calculates a global 4-element vector containing
(in this order): *evdwl* and *ecoul* for intramolecular pairs and
*evdwl* and *ecoul* for intermolecular pairs. Since molecules are
identified by their molecule IDs, the partitioning does not have to be
related to molecules, but the energies are tallied into the respective
slots depending on whether the molecule IDs of a pair are the same or
different. Compute *force/tally* calculates a global scalar (the force
magnitude) and a per atom 3-element vector (force contribution from
each atom). Compute *stress/tally* calculates a global scalar
different.
- Compute *force/tally* calculates a global scalar (the force magnitude)
and a per atom 3-element vector (force contribution from each atom).
- Compute *stress/tally* calculates a global scalar
(average of the diagonal elements of the stress tensor) and a per atom
vector (the 6 elements of stress tensor contributions from the
individual atom). As in :doc:`compute heat/flux <compute_heat_flux>`,
individual atom).
- As in :doc:`compute heat/flux <compute_heat_flux>`,
compute *heat/flux/tally* calculates a global vector of length 6,
where the first 3 components are the :math:`x`, :math:`y`, :math:`z`
components of the full heat flow vector,
and the next 3 components are the corresponding components
of just the convective portion of the flow, i.e. the
first term in the equation for :math:`\mathbf{Q}`.
Compute *heat/flux/virial/tally* calculates a global scalar (heat flow)
- Compute *heat/flux/virial/tally* calculates a global scalar (heat flow)
and a per atom 3-element vector
(contribution to the force acting over atoms in the first group
from individual atoms in both groups).

95
doc/src/dump.rst
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@ -137,7 +137,7 @@ Examples
dump myDump all atom/gz 100 dump.atom.gz
dump myDump all atom/zstd 100 dump.atom.zst
dump 2 subgroup atom 50 dump.run.bin
dump 2 subgroup atom 50 dump.run.mpiio.bin
dump 2 subgroup atom/mpiio 50 dump.run.mpiio.bin
dump 4a all custom 100 dump.myforce.* id type x y vx fx
dump 4b flow custom 100 dump.%.myforce id type c_myF[3] v_ke
dump 4b flow custom 100 dump.%.myforce id type c_myF[*] v_ke
@ -169,11 +169,12 @@ or multiple smaller files).
.. note::
Because periodic boundary conditions are enforced only on
timesteps when neighbor lists are rebuilt, the coordinates of an atom
written to a dump file may be slightly outside the simulation box.
Re-neighbor timesteps will not typically coincide with the timesteps
dump snapshots are written. See the :doc:`dump_modify pbc <dump_modify>` command if you with to force coordinates to be
Because periodic boundary conditions are enforced only on timesteps
when neighbor lists are rebuilt, the coordinates of an atom written
to a dump file may be slightly outside the simulation box.
Re-neighbor timesteps will not typically coincide with the
timesteps dump snapshots are written. See the :doc:`dump_modify
pbc <dump_modify>` command if you with to force coordinates to be
strictly inside the simulation box.
.. note::
@ -189,20 +190,21 @@ or multiple smaller files).
multiple processors, each of which owns a subset of the atoms.
For the *atom*, *custom*, *cfg*, and *local* styles, sorting is off by
default. For the *dcd*, *xtc*, *xyz*, and *molfile* styles, sorting by
atom ID is on by default. See the :doc:`dump_modify <dump_modify>` doc
page for details.
default. For the *dcd*, *xtc*, *xyz*, and *molfile* styles, sorting
by atom ID is on by default. See the :doc:`dump_modify <dump_modify>`
doc page for details.
The *atom/gz*, *cfg/gz*, *custom/gz*, *local/gz*, and *xyz/gz* styles are identical
in command syntax to the corresponding styles without "gz", however,
they generate compressed files using the zlib library. Thus the filename
suffix ".gz" is mandatory. This is an alternative approach to writing
compressed files via a pipe, as done by the regular dump styles, which
may be required on clusters where the interface to the high-speed network
disallows using the fork() library call (which is needed for a pipe).
For the remainder of this doc page, you should thus consider the *atom*
and *atom/gz* styles (etc) to be inter-changeable, with the exception
of the required filename suffix.
The *atom/gz*, *cfg/gz*, *custom/gz*, *local/gz*, and *xyz/gz* styles
are identical in command syntax to the corresponding styles without
"gz", however, they generate compressed files using the zlib
library. Thus the filename suffix ".gz" is mandatory. This is an
alternative approach to writing compressed files via a pipe, as done
by the regular dump styles, which may be required on clusters where
the interface to the high-speed network disallows using the fork()
library call (which is needed for a pipe). For the remainder of this
doc page, you should thus consider the *atom* and *atom/gz* styles
(etc) to be inter-changeable, with the exception of the required
filename suffix.
Similarly, the *atom/zstd*, *cfg/zstd*, *custom/zstd*, *local/zstd*,
and *xyz/zstd* styles are identical to the gz styles, but use the Zstd
@ -219,6 +221,11 @@ you should thus consider the *atom* and *atom/mpiio* styles (etc) to
be inter-changeable. The one exception is how the filename is
specified for the MPI-IO styles, as explained below.
.. warning::
The MPIIO package is currently unmaintained and has become
unreliable. Use with caution.
The precision of values output to text-based dump files can be
controlled by the :doc:`dump_modify format <dump_modify>` command and
its options.
@ -275,10 +282,11 @@ This bounding box is convenient for many visualization programs. The
meaning of the 6 character flags for "xx yy zz" is the same as above.
Note that the first two numbers on each line are now xlo_bound instead
of xlo, etc, since they represent a bounding box. See the :doc:`Howto triclinic <Howto_triclinic>` page for a geometric description
of triclinic boxes, as defined by LAMMPS, simple formulas for how the
6 bounding box extents (xlo_bound,xhi_bound,etc) are calculated from
the triclinic parameters, and how to transform those parameters to and
of xlo, etc, since they represent a bounding box. See the :doc:`Howto
triclinic <Howto_triclinic>` page for a geometric description of
triclinic boxes, as defined by LAMMPS, simple formulas for how the 6
bounding box extents (xlo_bound,xhi_bound,etc) are calculated from the
triclinic parameters, and how to transform those parameters to and
from other commonly used triclinic representations.
The "ITEM: ATOMS" line in each snapshot lists column descriptors for
@ -310,23 +318,24 @@ written to the dump file. This local data is typically calculated by
each processor based on the atoms it owns, but there may be zero or
more entities per atom, e.g. a list of bond distances. An explanation
of the possible dump local attributes is given below. Note that by
using input from the :doc:`compute property/local <compute_property_local>` command with dump local,
it is possible to generate information on bonds, angles, etc that can
be cut and pasted directly into a data file read by the
:doc:`read_data <read_data>` command.
using input from the :doc:`compute property/local
<compute_property_local>` command with dump local, it is possible to
generate information on bonds, angles, etc that can be cut and pasted
directly into a data file read by the :doc:`read_data <read_data>`
command.
Style *cfg* has the same command syntax as style *custom* and writes
extended CFG format files, as used by the
`AtomEye <http://li.mit.edu/Archive/Graphics/A/>`_ visualization
package. Since the extended CFG format uses a single snapshot of the
system per file, a wildcard "\*" must be included in the filename, as
discussed below. The list of atom attributes for style *cfg* must
begin with either "mass type xs ys zs" or "mass type xsu ysu zsu"
since these quantities are needed to write the CFG files in the
appropriate format (though the "mass" and "type" fields do not appear
explicitly in the file). Any remaining attributes will be stored as
"auxiliary properties" in the CFG files. Note that you will typically
want to use the :doc:`dump_modify element <dump_modify>` command with
extended CFG format files, as used by the `AtomEye
<http://li.mit.edu/Archive/Graphics/A/>`_ visualization package.
Since the extended CFG format uses a single snapshot of the system per
file, a wildcard "\*" must be included in the filename, as discussed
below. The list of atom attributes for style *cfg* must begin with
either "mass type xs ys zs" or "mass type xsu ysu zsu" since these
quantities are needed to write the CFG files in the appropriate format
(though the "mass" and "type" fields do not appear explicitly in the
file). Any remaining attributes will be stored as "auxiliary
properties" in the CFG files. Note that you will typically want to
use the :doc:`dump_modify element <dump_modify>` command with
CFG-formatted files, to associate element names with atom types, so
that AtomEye can render atoms appropriately. When unwrapped
coordinates *xsu*, *ysu*, and *zsu* are requested, the nominal AtomEye
@ -452,6 +461,11 @@ use the :doc:`read_dump <read_dump>` command or perform other
post-processing, just as if the dump file was not written using
MPI-IO.
.. warning::
The MPIIO package is currently unmaintained and has become
unreliable. Use with caution.
Note that MPI-IO dump files are one large file which all processors
write to. You thus cannot use the "%" wildcard character described
above in the filename since that specifies generation of multiple
@ -708,8 +722,9 @@ are part of the MPIIO package. They are only enabled if LAMMPS was
built with that package. See the :doc:`Build package <Build_package>`
doc page for more info.
The *xtc* style is part of the MISC package. It is only enabled if
LAMMPS was built with that package. See the :doc:`Build package <Build_package>` page for more info.
The *xtc* and *dcd* styles are part of the EXTRA-DUMP package. They
are only enabled if LAMMPS was built with that package. See the
:doc:`Build package <Build_package>` page for more info.
Related commands
""""""""""""""""

165
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@ -17,13 +17,14 @@ Syntax
* one or more keyword/value pairs may be appended
* these keywords apply to various dump styles
* keyword = *append* or *at* or *buffer* or *delay* or *element* or *every* or *fileper* or *first* or *flush* or *format* or *header* or *image* or *label* or *maxfiles* or *nfile* or *pad* or *pbc* or *precision* or *region* or *refresh* or *scale* or *sfactor* or *sort* or *tfactor* or *thermo* or *thresh* or *time* or *units* or *unwrap*
* keyword = *append* or *at* or *balance* or *buffer* or *delay* or *element* or *every* or *every/time* or *fileper* or *first* or *flush* or *format* or *header* or *image* or *label* or *maxfiles* or *nfile* or *pad* or *pbc* or *precision* or *region* or *refresh* or *scale* or *sfactor* or *sort* or *tfactor* or *thermo* or *thresh* or *time* or *units* or *unwrap*
.. parsed-literal::
*append* arg = *yes* or *no*
*at* arg = N
N = index of frame written upon first dump
*balance* arg = *yes* or *no*
*buffer* arg = *yes* or *no*
*delay* arg = Dstep
Dstep = delay output until this timestep
@ -32,6 +33,9 @@ Syntax
*every* arg = N
N = dump every this many timesteps
N can be a variable (see below)
*every/time* arg = Delta
Delta = dump every this interval in simulation time (time units)
Delta can be a variable (see below)
*fileper* arg = Np
Np = write one file for every this many processors
*first* arg = *yes* or *no*
@ -197,11 +201,19 @@ will be accepted.
----------
The *every* keyword changes the dump frequency originally specified by
the :doc:`dump <dump>` command to a new value. The every keyword can be
specified in one of two ways. It can be a numeric value in which case
it must be > 0. Or it can be an :doc:`equal-style variable <variable>`,
which should be specified as v_name, where name is the variable name.
The *every* keyword can be used with any dump style except the *dcd*
and *xtc* styles. It does two things. It specifies that the interval
between dump snapshots will be set in timesteps, which is the default
if the *every* or *every/time* keywords are not used. See the
*every/time* keyword for how to specify the interval in simulation
time, i.e. in time units of the :doc:`units <units>` command. The
*every* keyword also sets the interval value, which overrides the dump
frequency originally specified by the :doc:`dump <dump>` command.
The *every* keyword can be specified in one of two ways. It can be a
numeric value in which case it must be > 0. Or it can be an
:doc:`equal-style variable <variable>`, which should be specified as
v_name, where name is the variable name.
In this case, the variable is evaluated at the beginning of a run to
determine the next timestep at which a dump snapshot will be written
@ -210,11 +222,12 @@ determine the next timestep, etc. Thus the variable should return
timestep values. See the stagger() and logfreq() and stride() math
functions for :doc:`equal-style variables <variable>`, as examples of
useful functions to use in this context. Other similar math functions
could easily be added as options for :doc:`equal-style variables <variable>`. Also see the next() function, which allows
use of a file-style variable which reads successive values from a
file, each time the variable is evaluated. Used with the *every*
keyword, if the file contains a list of ascending timesteps, you can
output snapshots whenever you wish.
could easily be added as options for :doc:`equal-style variables
<variable>`. Also see the next() function, which allows use of a
file-style variable which reads successive values from a file, each
time the variable is evaluated. Used with the *every* keyword, if the
file contains a list of ascending timesteps, you can output snapshots
whenever you wish.
Note that when using the variable option with the *every* keyword, you
need to use the *first* option if you want an initial snapshot written
@ -255,14 +268,103 @@ in file tmp.times:
----------
The *every/time* keyword can be used with any dump style except the
*dcd* and *xtc* styles. It does two things. It specifies that the
interval between dump snapshots will be set in simulation time,
i.e. in time units of the :doc:`units <units>` command. This can be
useful when the timestep size varies during a simulation run, e.g. by
use of the :doc:`fix dt/reset <fix_dt_reset>` command. The default is
to specify the interval in timesteps; see the *every* keyword. The
*every/time* command also sets the interval value.
.. note::
If you wish dump styles *atom*, *custom*, *local*, or *xyz* to
include the simulation time as a field in the header portion of
each snapshot, you also need to use the dump_modify *time* keyword
with a setting of *yes*. See its documentation below.
Note that since snapshots are output on simulation steps, each
snapshot will be written on the first timestep whose associated
simulation time is >= the exact snapshot time value.
As with the *every* option, the *Delta* value can be specified in one
of two ways. It can be a numeric value in which case it must be >
0.0. Or it can be an :doc:`equal-style variable <variable>`, which
should be specified as v_name, where name is the variable name.
In this case, the variable is evaluated at the beginning of a run to
determine the next simulation time at which a dump snapshot will be
written out. On that timestep the variable will be evaluated again to
determine the next simulation time, etc. Thus the variable should
return values in time units. Note the current timestep or simulation
time can be used in an :doc:`equal-style variables <variable>` since
they are both thermodynamic keywords. Also see the next() function,
which allows use of a file-style variable which reads successive
values from a file, each time the variable is evaluated. Used with
the *every/time* keyword, if the file contains a list of ascending
simulation times, you can output snapshots whenever you wish.
Note that when using the variable option with the *every/time*
keyword, you need to use the *first* option if you want an initial
snapshot written to the dump file. The *every/time* keyword cannot be
used with the dump *dcd* style.
For example, the following commands will write snapshots at successive
simulation times which grow by a factor of 1.5 with each interval.
The dt value used in the variable is to avoid a zero result when the
initial simulation time is 0.0.
.. code-block:: LAMMPS
variable increase equal 1.5*(time+dt)
dump 1 all atom 100 tmp.dump
dump_modify 1 every/time v_increase first yes
The following commands would write snapshots at the times listed in
file tmp.times:
.. code-block:: LAMMPS
variable f file tmp.times
variable s equal next(f)
dump 1 all atom 100 tmp.dump
dump_modify 1 every/time v_s
.. note::
When using a file-style variable with the *every/time* keyword, the
file of timesteps must list a first time that is beyond the time
associated with the current timestep (e.g. it cannot be 0.0). And
it must list one or more times beyond the length of the run you
perform. This is because the dump command will generate an error
if the next time it reads from the file is not a value greater than
the current time. Thus if you wanted output at times 0,15,100 of a
run of length 100 in simulation time, the file should contain the
values 15,100,101 and you should also use the dump_modify first
command. Any final value > 100 could be used in place of 101.
----------
The *first* keyword determines whether a dump snapshot is written on
the very first timestep after the dump command is invoked. This will
always occur if the current timestep is a multiple of N, the frequency
specified in the :doc:`dump <dump>` command, including timestep 0. But
if this is not the case, a dump snapshot will only be written if the
setting of this keyword is *yes*\ . If it is *no*, which is the
always occur if the current timestep is a multiple of $N$, the
frequency specified in the :doc:`dump <dump>` command or
:doc:`dump_modify every <dump_modify>` command, including timestep 0.
It will also always occur if the current simulation time is a multiple
of *Delta*, the time interval specified in the doc:`dump_modify
every/time <dump_modify>` command.
But if this is not the case, a dump snapshot will only be written if
the setting of this keyword is *yes*\ . If it is *no*, which is the
default, then it will not be written.
Note that if the argument to the :doc:`dump_modify every
<dump_modify>` doc:`dump_modify every/time <dump_modify>` commands is
a variable and not a numeric value, then specifying *first yes* is the
only way to write a dump snapshot on the first timestep after the dump
command is invoked.
----------
The *flush* keyword determines whether a flush operation is invoked
@ -342,10 +444,10 @@ The *fileper* keyword is documented below with the *nfile* keyword.
----------
The *header* keyword toggles whether the dump file will include a header.
Excluding a header will reduce the size of the dump file for fixes such as
:doc:`fix pair/tracker <fix_pair_tracker>` which do not require the information
typically written to the header.
The *header* keyword toggles whether the dump file will include a
header. Excluding a header will reduce the size of the dump file for
fixes such as :doc:`fix pair/tracker <fix_pair_tracker>` which do not
require the information typically written to the header.
----------
@ -561,9 +663,19 @@ The dump *local* style cannot be sorted by atom ID, since there are
typically multiple lines of output per atom. Some dump styles, such
as *dcd* and *xtc*, require sorting by atom ID to format the output
file correctly. If multiple processors are writing the dump file, via
the "%" wildcard in the dump filename, then sorting cannot be
the "%" wildcard in the dump filename and the *nfile* or *fileper*
keywords are set to non-default values (i.e. the number of dump file
pieces is not equal to the number of procs), then sorting cannot be
performed.
In a parallel run, the per-processor dump file pieces can have
significant imbalance in number of lines of per-atom info. The *balance*
keyword determines whether the number of lines in each processor
snapshot are balanced to be nearly the same. A balance value of *no*
means no balancing will be done, while *yes* means balancing will be
performed. This balancing preserves dump sorting order. For a serial
run, this option is ignored since the output is already balanced.
.. note::
Unless it is required by the dump style, sorting dump file
@ -639,16 +751,20 @@ threshold criterion is met. Otherwise it is not met.
----------
The *time* keyword only applies to the dump *atom*, *custom*, and
*local* styles (and their COMPRESS package versions *atom/gz*,
*custom/gz* and *local/gz*\ ). If set to *yes*, each frame will will
contain two extra lines before the "ITEM: TIMESTEP" entry:
The *time* keyword only applies to the dump *atom*, *custom*, *local*,
and *xyz* styles (and their COMPRESS package versions *atom/gz*,
*custom/gz* and *local/gz*\ ). For the first 3 styles, if set to
*yes*, each frame will will contain two extra lines before the "ITEM:
TIMESTEP" entry:
.. parsed-literal::
ITEM: TIME
\<elapsed time\>
For the *xyz* style, the simulation time is included on the same line
as the timestep value.
This will output the current elapsed simulation time in current
time units equivalent to the :doc:`thermo keyword <thermo_style>` *time*\ .
This is to simplify post-processing of trajectories using a variable time
@ -725,6 +841,7 @@ Default
The option defaults are
* append = no
* balance = no
* buffer = yes for dump styles *atom*, *custom*, *loca*, and *xyz*
* element = "C" for every atom type
* every = whatever it was set to via the :doc:`dump <dump>` command

9
doc/src/dynamical_matrix.rst
View File

@ -1,8 +1,11 @@
.. index:: dynamical_matrix
.. index:: dynamical_matrix/kk
dynamical_matrix command
========================
Accelerator Variants: dynamical_matrix/kk
Syntax
""""""
@ -56,6 +59,12 @@ If the style eskm is selected, the dynamical matrix will be in units of
inverse squared femtoseconds. These units will then conveniently leave
frequencies in THz.
----------
.. include:: accel_styles.rst
----------
Restrictions
""""""""""""

5
doc/src/fix.rst
View File

@ -240,8 +240,6 @@ accelerated styles exist.
* :doc:`latte <fix_latte>` - wrapper on LATTE density-functional tight-binding code
* :doc:`lb/fluid <fix_lb_fluid>` -
* :doc:`lb/momentum <fix_lb_momentum>` -
* :doc:`lb/pc <fix_lb_pc>` -
* :doc:`lb/rigid/pc/sphere <fix_lb_rigid_pc_sphere>` -
* :doc:`lb/viscous <fix_lb_viscous>` -
* :doc:`lineforce <fix_lineforce>` - constrain atoms to move in a line
* :doc:`manifoldforce <fix_manifoldforce>` - restrain atoms to a manifold during minimization
@ -271,7 +269,8 @@ accelerated styles exist.
* :doc:`npt/eff <fix_nh_eff>` - NPT for nuclei and electrons in the electron force field model
* :doc:`npt/sphere <fix_npt_sphere>` - NPT for spherical particles
* :doc:`npt/uef <fix_nh_uef>` - NPT style time integration with diagonal flow
* :doc:`numdiff <fix_numdiff>` - compute derivatives of per-atom data from finite differences
* :doc:`numdiff <fix_numdiff>` - numerically approximate atomic forces using finite energy differences
* :doc:`numdiff/virial <fix_numdiff_virial>` - numerically approximate virial stress tensor using finite energy differences
* :doc:`nve <fix_nve>` - constant NVE time integration
* :doc:`nve/asphere <fix_nve_asphere>` - NVE for aspherical particles
* :doc:`nve/asphere/noforce <fix_nve_asphere_noforce>` - NVE for aspherical particles without forces

2
doc/src/fix_addtorque.rst
View File

@ -99,7 +99,7 @@ invoked by the :doc:`minimize <minimize>` command.
Restrictions
""""""""""""
This fix is part of the MISC package. It is only enabled if
This fix is part of the EXTRA-FIX package. It is only enabled if
LAMMPS was built with that package. See the :doc:`Build package
<Build_package>` page for more info.

75
doc/src/fix_charge_regulation.rst
View File

@ -20,13 +20,13 @@ Syntax
.. parsed-literal::
keyword = *pH*, *pKa*, *pKb*, *pIp*, *pIm*, *pKs*, *acid_type*, *base_type*, *lunit_nm*, *temp*, *tempfixid*, *nevery*, *nmc*, *xrd*, *seed*, *tag*, *group*, *onlysalt*, *pmcmoves*
keyword = *pH*, *pKa*, *pKb*, *pIp*, *pIm*, *pKs*, *acid_type*, *base_type*, *lunit_nm*, *temp*, *tempfixid*, *nevery*, *nmc*, *rxd*, *seed*, *tag*, *group*, *onlysalt*, *pmcmoves*
*pH* value = pH of the solution (can be specified as an equal-style variable)
*pKa* value = acid dissociation constant
*pKb* value = base dissociation constant
*pIp* value = chemical potential of free cations
*pIm* value = chemical potential of free anions
*pKs* value = solution self-dissociation constant
*pKa* value = acid dissociation constant (in the -log10 representation)
*pKb* value = base dissociation constant (in the -log10 representation)
*pIp* value = activity (effective concentration) of free cations (in the -log10 representation)
*pIm* value = activity (effective concentration) of free anions (in the -log10 representation)
*pKs* value = solvent self-dissociation constant (in the -log10 representation)
*acid_type* = atom type of acid groups
*base_type* = atom type of base groups
*lunit_nm* value = unit length used by LAMMPS (# in the units of nanometers)
@ -34,7 +34,7 @@ Syntax
*tempfixid* value = fix ID of temperature thermostat
*nevery* value = invoke this fix every nevery steps
*nmc* value = number of charge regulation MC moves to attempt every nevery steps
*xrd* value = cutoff distance for acid/base reaction
*rxd* value = cutoff distance for acid/base reaction
*seed* value = random # seed (positive integer)
*tag* value = yes or no (yes: The code assign unique tags to inserted ions; no: The tag of all inserted ions is "0")
*group* value = group-ID, inserted ions are assigned to group group-ID. Can be used multiple times to assign inserted ions to multiple groups.
@ -47,7 +47,7 @@ Examples
""""""""
.. code-block:: LAMMPS
fix chareg all charge/regulation 1 2 acid_type 3 base_type 4 pKa 5 pKb 7 lb 1.0 nevery 200 nexchange 200 seed 123 tempfixid fT
fix chareg all charge/regulation 1 2 acid_type 3 base_type 4 pKa 5.0 pKb 6.0 pH 7.0 pIp 3.0 pIm 3.0 nevery 200 nmc 200 seed 123 tempfixid fT
fix chareg all charge/regulation 1 2 pIp 3 pIm 3 onlysalt yes 2 -1 seed 123 tag yes temp 1.0
@ -92,7 +92,11 @@ where the fix attempts to charge :math:`\mathrm{A}` (discharge
:math:`\mathrm{A}^-`) to :math:`\mathrm{A}^-` (:math:`\mathrm{A}`) and
insert (delete) a proton (atom type 2). Besides, the fix implements
self-ionization reaction of water :math:`\emptyset \rightleftharpoons
\mathrm{H}^++\mathrm{OH}^-`. However, this approach is highly
\mathrm{H}^++\mathrm{OH}^-`.
However, this approach is highly
inefficient at :math:`\mathrm{pH} \approx 7` when the concentration of
both protons and hydroxyl ions is low, resulting in a relatively low
acceptance rate of MC moves.
@ -102,24 +106,31 @@ reactions, which can be easily achieved via
.. code-block:: LAMMPS
fix acid_reaction all charge/regulation 4 5 acid_type 1 pH 7.0 pKa 5.0 pIp 2.0 pIm 2.0
fix acid_reaction2 all charge/regulation 4 5 acid_type 1 pH 7.0 pKa 5.0 pIp 2.0 pIm 2.0
where particles of atom type 4 and 5 are the salt cations and anions,
both at chemical potential pI=2.0, see :ref:`(Curk1) <Curk1>` and
where particles of atom type 4 and 5 are the salt cations and anions, both at activity (effective concentration) of :math:`10^{-2}` mol/l, see :ref:`(Curk1) <Curk1>` and
:ref:`(Landsgesell) <Landsgesell>` for more details.
Similarly, we could have simultaneously added a base ionization reaction
(:math:`\mathrm{B} \rightleftharpoons \mathrm{B}^++\mathrm{OH}^-`)
We could have simultaneously added a base ionization reaction (:math:`\mathrm{B} \rightleftharpoons \mathrm{B}^++\mathrm{OH}^-`)
.. code-block:: LAMMPS
fix base_reaction all charge/regulation 2 3 base_type 6 pH 7.0 pKb 6.0 pIp 7.0 pIm 7.0
fix acid_base_reaction all charge/regulation 2 3 acid_type 1 base_type 6 pH 7.0 pKa 5.0 pKb 6.0 pIp 7.0 pIm 7.0
where the fix will attempt to charge :math:`\mathrm{B}` (discharge
:math:`\mathrm{B}^+`) to :math:`\mathrm{B}^+` (:math:`\mathrm{B}`) and
insert (delete) a hydroxyl ion :math:`\mathrm{OH}^-` of atom type 3. If
neither the acid or the base type is specified, for example,
insert (delete) a hydroxyl ion :math:`\mathrm{OH}^-` of atom type 3.
Dissociated ions and salt ions can be combined into a single particle type, which reduces the number of necessary MC moves and increases sampling performance, see :ref:`(Curk1) <Curk1>`. The :math:`\mathrm{H}^+` and monovalent salt cation (:math:`\mathrm{S}^+`) are combined into a single particle type, :math:`\mathrm{X}^+ = \{\mathrm{H}^+, \mathrm{S}^+\}`. In this case "pIp" refers to the effective concentration of the combined cation type :math:`\mathrm{X}^+` and its value is determined by :math:`10^{-\mathrm{pIp}} = 10^{-\mathrm{pH}} + 10^{-\mathrm{pSp}}`, where :math:`10^{-\mathrm{pSp}}` is the effective concentration of salt cations. For example, at pH=7 and pSp=6 we would find pIp~5.958 and the command that performs reactions with combined ions could read,
.. code-block:: LAMMPS
fix acid_reaction_combined all charge/regulation 2 3 acid_type 1 pH 7.0 pKa 5.0 pIp 5.958 pIm 5.958
If neither the acid or the base type is specified, for example,
.. code-block:: LAMMPS
@ -127,11 +138,11 @@ neither the acid or the base type is specified, for example,
the fix simply inserts or deletes an ion pair of a free cation (atom
type 4) and a free anion (atom type 5) as done in a conventional
grand-canonical MC simulation.
grand-canonical MC simulation. Multivalent ions can be inserted (deleted) by using the *onlysalt* keyword.
The fix is compatible with LAMMPS sub-packages such as *molecule* or
*rigid*. That said, the acid and base particles can be part of larger
*rigid*. The acid and base particles can be part of larger
molecules or rigid bodies. Free ions that are inserted to or deleted
from the system must be defined as single particles (no bonded
interactions allowed) and cannot be part of larger molecules or rigid
@ -153,14 +164,14 @@ Langevin thermostat:
fix fT all langevin 1.0 1.0 1.0 123
fix_modify fT temp dtemp
The chemical potential units (e.g. pH) are in the standard log10
The units of pH, pKa, pKb, pIp, pIm are considered to be in the standard -log10
representation assuming reference concentration :math:`\rho_0 =
\mathrm{mol}/\mathrm{l}`. Therefore, to perform the internal unit
conversion, the length (in nanometers) of the LAMMPS unit length must be
specified via *lunit_nm* (default is set to the Bjerrum length in water
at room temperature *lunit_nm* = 0.71nm). For example, in the dilute
ideal solution limit, the concentration of free ions will be
:math:`c_\mathrm{I} = 10^{-\mathrm{pIp}}\mathrm{mol}/\mathrm{l}`.
\mathrm{mol}/\mathrm{l}`. For example, in the dilute
ideal solution limit, the concentration of free cations will be
:math:`c_\mathrm{I} = 10^{-\mathrm{pIp}}\mathrm{mol}/\mathrm{l}`. To perform the internal unit
conversion, the the value of the LAMMPS unit length must be
specified in nanometers via *lunit_nm*. The default value is set to the Bjerrum length in water
at room temperature (0.71 nm), *lunit_nm* = 0.71.
The temperature used in MC acceptance probability is set by *temp*. This
temperature should be the same as the temperature set by the molecular
@ -171,10 +182,10 @@ thermostat fix-ID is *fT*. The inserted particles attain a random
velocity corresponding to the specified temperature. Using *tempfixid*
overrides any fixed temperature set by *temp*.
The *xrd* keyword can be used to restrict the inserted/deleted
The *rxd* keyword can be used to restrict the inserted/deleted
counterions to a specific radial distance from an acid or base particle
that is currently participating in a reaction. This can be used to
simulate more realist reaction dynamics. If *xrd* = 0 or *xrd* > *L* /
simulate more realist reaction dynamics. If *rxd* = 0 or *rxd* > *L* /
2, where *L* is the smallest box dimension, the radial restriction is
automatically turned off and free ion can be inserted or deleted
anywhere in the simulation box.
@ -258,18 +269,18 @@ Default
pH = 7.0; pKa = 100.0; pKb = 100.0; pIp = 5.0; pIm = 5.0; pKs = 14.0;
acid_type = -1; base_type = -1; lunit_nm = 0.71; temp = 1.0; nevery =
100; nmc = 100; xrd = 0; seed = 0; tag = no; onlysalt = no, pmcmoves =
100; nmc = 100; rxd = 0; seed = 0; tag = no; onlysalt = no, pmcmoves =
[1/3, 1/3, 1/3], group-ID = all
----------
.. _Curk1:
**(Curk1)** T. Curk, J. Yuan, and E. Luijten, "Coarse-grained simulation of charge regulation using LAMMPS", preprint (2021).
**(Curk1)** T. Curk, J. Yuan, and E. Luijten, "Accelerated simulation method for charge regulation effects", JCP 156 (2022).
.. _Curk2:
**(Curk2)** T. Curk and E. Luijten, "Charge-regulation effects in nanoparticle self-assembly", PRL (2021)
**(Curk2)** T. Curk and E. Luijten, "Charge-regulation effects in nanoparticle self-assembly", PRL 126 (2021)
.. _Landsgesell:

18
doc/src/fix_dt_reset.rst
View File

@ -78,13 +78,20 @@ outer loop (largest) timestep, which is the same timestep that the
Note that the cumulative simulation time (in time units), which
accounts for changes in the timestep size as a simulation proceeds,
can be accessed by the :doc:`thermo_style time <thermo_style>` keyword.
can be accessed by the :doc:`thermo_style time <thermo_style>`
keyword.
Also note that the :doc:`dump_modify every/time <dump_modify>` option
allows dump files to be written at intervals specified by simulation
time, rather than by timesteps. Simulation time is in time units;
see the :doc:`units <units>` doc page for details.
Restart, fix_modify, output, run start/stop, minimize info
"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""
No information about this fix is written to :doc:`binary restart files <restart>`. None of the :doc:`fix_modify <fix_modify>` options
are relevant to this fix.
No information about this fix is written to :doc:`binary restart files
<restart>`. None of the :doc:`fix_modify <fix_modify>` options are
relevant to this fix.
This fix computes a global scalar which can be accessed by various
:doc:`output commands <Howto_output>`. The scalar stores the last
@ -93,7 +100,8 @@ timestep on which the timestep was reset to a new value.
The scalar value calculated by this fix is "intensive".
No parameter of this fix can be used with the *start/stop* keywords of
the :doc:`run <run>` command. This fix is not invoked during :doc:`energy minimization <minimize>`.
the :doc:`run <run>` command. This fix is not invoked during
:doc:`energy minimization <minimize>`.
Restrictions
""""""""""""
@ -102,7 +110,7 @@ Restrictions
Related commands
""""""""""""""""
:doc:`timestep <timestep>`
:doc:`timestep <timestep>`, :doc:`dump_modify every/time <dump_modify>`
Default
"""""""

9
doc/src/fix_gcmc.rst
View File

@ -444,8 +444,15 @@ doc page for more info.
Do not set "neigh_modify once yes" or else this fix will never be
called. Reneighboring is required.
Only usable for 3D simulations.
Can be run in parallel, but aspects of the GCMC part will not scale
well in parallel. Only usable for 3D simulations.
well in parallel. Currently, molecule translations and rotations
are not supported with more than one MPI process.
It is still possible to do parallel molecule exchange without
translation and rotation moves by setting MC moves to zero
and/or by using the *mcmoves* keyword with *Pmoltrans* = *Pmolrotate* = 0 .
When using fix gcmc in combination with fix shake or fix rigid,
only GCMC exchange moves are supported, so the argument

4
doc/src/fix_langevin_drude.rst
View File

@ -40,7 +40,7 @@ Example input scripts available: examples/PACKAGES/drude
Description
"""""""""""
Apply two Langevin thermostats as described in :ref:`(Jiang) <Jiang1>` for
Apply two Langevin thermostats as described in :ref:`(Jiang1) <Jiang1>` for
thermalizing the reduced degrees of freedom of Drude oscillators.
This link describes how to use the :doc:`thermalized Drude oscillator model <Howto_drude>` in LAMMPS and polarizable models in LAMMPS
are discussed on the :doc:`Howto polarizable <Howto_polarizable>` doc
@ -300,5 +300,5 @@ The option defaults are zero = no.
.. _Jiang1:
**(Jiang)** Jiang, Hardy, Phillips, MacKerell, Schulten, and Roux, J
**(Jiang1)** Jiang, Hardy, Phillips, MacKerell, Schulten, and Roux, J
Phys Chem Lett, 2, 87-92 (2011).

451
doc/src/fix_lb_fluid.rst
View File

@ -12,55 +12,65 @@ Syntax
* ID, group-ID are documented in :doc:`fix <fix>` command
* lb/fluid = style name of this fix command
* nevery = update the lattice-Boltzmann fluid every this many timesteps
* LBtype = 1 to use the standard finite difference LB integrator,
2 to use the LB integrator of :ref:`Ollila et al. <Ollila>`
* nevery = update the lattice-Boltzmann fluid every this many timesteps (should normally be 1)
* viscosity = the fluid viscosity (units of mass/(time\*length)).
* density = the fluid density.
* zero or more keyword/value pairs may be appended
* keyword = *setArea* or *setGamma* or *scaleGamma* or *dx* or *dm* or *a0* or *noise* or *calcforce* or *trilinear* or *D3Q19* or *read_restart* or *write_restart* or *zwall_velocity* or *bodyforce* or *printfluid*
* keyword = *dx* or *dm* or *noise* or *stencil* or *read_restart* or *write_restart* or *zwall_velocity* or *pressurebcx* or *bodyforce* or *D3Q19* or *dumpxdmf* or *dof* or *scaleGamma* or *a0* or *npits* or *wp* or *sw*
.. parsed-literal::
*setArea* values = type node_area
type = atom type (1-N)
node_area = portion of the surface area of the composite object associated with the particular atom type (used when the force coupling constant is set by default).
*setGamma* values = gamma
gamma = user set value for the force coupling constant.
*scaleGamma* values = type gammaFactor
type = atom type (1-N)
gammaFactor = factor to scale the *setGamma* gamma value by, for the specified atom type.
*dx* values = dx_LB = the lattice spacing.
*dm* values = dm_LB = the lattice-Boltzmann mass unit.
*a0* values = a_0_real = the square of the speed of sound in the fluid.
*noise* values = Temperature seed
Temperature = fluid temperature.
seed = random number generator seed (positive integer)
*calcforce* values = N forcegroup-ID
N = output the force and torque every N timesteps
forcegroup-ID = ID of the particle group to calculate the force and torque of
*trilinear* values = none (used to switch from the default Peskin interpolation stencil to the trilinear stencil).
*D3Q19* values = none (used to switch from the default D3Q15, 15 velocity lattice, to the D3Q19, 19 velocity lattice).
*stencil* values = 2 (trilinear stencil, the default), 3 (3-point immersed boundary stencil), or 4 (4-point Keys' interpolation stencil)
*read_restart* values = restart file = name of the restart file to use to restart a fluid run.
*write_restart* values = N = write a restart file every N MD timesteps.
*zwall_velocity* values = velocity_bottom velocity_top = velocities along the y-direction of the bottom and top walls (located at z=zmin and z=zmax).
*pressurebcx* values = pgradav = imposes a pressure jump at the (periodic) x-boundary of pgradav*Lx*1000.
*bodyforce* values = bodyforcex bodyforcey bodyforcez = the x,y and z components of a constant body force added to the fluid.
*printfluid* values = N = print the fluid density and velocity at each grid point every N timesteps.
*D3Q19* values = none (used to switch from the default D3Q15, 15 velocity lattice, to the D3Q19, 19 velocity lattice).
*dumpxdmf* values = N file timeI
N = output the force and torque every N timesteps
file = output file name
timeI = 1 (use simulation time to index xdmf file), 0 (use output frame number to index xdmf file)
*dof* values = dof = specify the number of degrees of freedom for temperature calculation
*scaleGamma* values = type gammaFactor
type = atom type (1-N)
gammaFactor = factor to scale the *setGamma* gamma value by, for the specified atom type.
*a0* values = a_0_real = the square of the speed of sound in the fluid.
*npits* values = npits h_p l_p l_pp l_e
npits = number of pit regions
h_p = z-height of pit regions (floor to bottom of slit)
l_p = x-length of pit regions
l_pp = x-length of slit regions between consecutive pits
l_e = x-length of slit regions at ends
*wp* values = w_p = y-width of slit regions (defaults to full width if not present or if sw active)
*sw* values = none (turns on y-sidewalls (in xz plane) if npits option active)
Examples
""""""""
.. code-block:: LAMMPS
fix 1 all lb/fluid 1 2 1.0 1.0 setGamma 13.0 dx 4.0 dm 10.0 calcforce sphere1
fix 1 all lb/fluid 1 1 1.0 0.0009982071 setArea 1 1.144592082 dx 2.0 dm 0.3 trilinear noise 300.0 8979873
fix 1 all lb/fluid 1 1.0 0.0009982071 dx 1.2 dm 0.001
fix 1 all lb/fluid 1 1.0 0.0009982071 dx 1.2 dm 0.001 noise 300.0 2761
fix 1 all lb/fluid 1 1.0 1.0 dx 4.0 dm 10.0 dumpxdmf 500 fflow 0 pressurebcx 0.01 npits 2 20 40 5 0 wp 30
Description
"""""""""""
Implement a lattice-Boltzmann fluid on a uniform mesh covering the LAMMPS
simulation domain. The MD particles described by *group-ID* apply a velocity
dependent force to the fluid.
.. versionchanged:: 24Mar2022
Implement a lattice-Boltzmann fluid on a uniform mesh covering the
LAMMPS simulation domain. Note that this fix was updated in 2022 and is
not backward compatible with the previous version. If you need the
previous version, please download an older version of LAMMPS. The MD
particles described by *group-ID* apply a velocity dependent force to
the fluid.
The lattice-Boltzmann algorithm solves for the fluid motion governed by
the Navier Stokes equations,
@ -86,28 +96,23 @@ respectively. Here, we have implemented
\sigma_{\alpha \beta} = -P_{\alpha \beta} = -\rho a_0 \delta_{\alpha \beta}
with :math:`a_0` set to :math:`\frac{1}{3} \frac{dx}{dt}^2` by default.
You should not normally need to change this default.
The algorithm involves tracking the time evolution of a set of partial
distribution functions which evolve according to a velocity
discretized version of the Boltzmann equation,
distribution functions which evolve according to a velocity discretized
version of the Boltzmann equation,
.. math::
\left(\partial_t + e_{i\alpha}\partial_{\alpha}\right)f_i = -\frac{1}{\tau}\left(f_i - f_i^{eq}\right) + W_i
where the first term on the right hand side represents a single time
relaxation towards the equilibrium distribution function, and :math:`\tau` is a
parameter physically related to the viscosity. On a technical note,
we have implemented a 15 velocity model (D3Q15) as default; however,
the user can switch to a 19 velocity model (D3Q19) through the use of
the *D3Q19* keyword. This fix provides the user with the choice of
two algorithms to solve this equation, through the specification of
the keyword *LBtype*\ . If *LBtype* is set equal to 1, the standard
finite difference LB integrator is used. If *LBtype* is set equal to
2, the algorithm of :ref:`Ollila et al. <Ollila>` is used.
Physical variables are then defined in terms of moments of the distribution
functions,
relaxation towards the equilibrium distribution function, and
:math:`\tau` is a parameter physically related to the viscosity. On a
technical note, we have implemented a 15 velocity model (D3Q15) as
default; however, the user can switch to a 19 velocity model (D3Q19)
through the use of the *D3Q19* keyword. Physical variables are then
defined in terms of moments of the distribution functions,
.. math::
@ -115,7 +120,7 @@ functions,
\rho u_{\alpha} = & \displaystyle\sum\limits_{i} f_i e_{i\alpha}
Full details of the lattice-Boltzmann algorithm used can be found in
:ref:`Mackay et al. <fluid-Mackay>`.
:ref:`Denniston et al. <fluid-Denniston>`.
The fluid is coupled to the MD particles described by *group-ID* through
a velocity dependent force. The contribution to the fluid force on a
@ -127,90 +132,64 @@ calculated as:
{\bf F}_{j \alpha} = \gamma \left({\bf v}_n - {\bf u}_f \right) \zeta_{j\alpha}
where :math:`\mathbf{v}_n` is the velocity of the MD particle,
:math:`\mathbf{u}_f` is the fluid
velocity interpolated to the particle location, and :math:`\gamma` is the force
coupling constant. :math:`\zeta` is a weight assigned to the grid point,
obtained by distributing the particle to the nearest lattice sites.
For this, the user has the choice between a trilinear stencil, which
provides a support of 8 lattice sites, or the immersed boundary method
Peskin stencil, which provides a support of 64 lattice sites. While
the Peskin stencil is seen to provide more stable results, the
trilinear stencil may be better suited for simulation of objects close
to walls, due to its smaller support. Therefore, by default, the
Peskin stencil is used; however the user may switch to the trilinear
stencil by specifying the keyword, *trilinear*\ .
:math:`\mathbf{u}_f` is the fluid velocity interpolated to the particle
location, and :math:`\gamma` is the force coupling constant. This
force, as with most forces in LAMMPS, and hence the velocities, are
calculated at the half-time step. :math:`\zeta` is a weight assigned to
the grid point, obtained by distributing the particle to the nearest
lattice sites.
By default, the force coupling constant, :math:`\gamma`, is calculated
The force coupling constant, :math:`\gamma`, is calculated
according to
.. math::
\gamma = \frac{2m_um_v}{m_u+m_v}\left(\frac{1}{\Delta t_{collision}}\right)
\gamma = \frac{2m_um_v}{m_u+m_v}\left(\frac{1}{\Delta t}\right)
Here, :math:`m_v` is the mass of the MD particle, :math:`m_u` is a
representative fluid mass at the particle location, and :math:`\Delta
t_{collision}` is a collision time, chosen such that
:math:`\frac{\tau}{\Delta t_{collision}} = 1` (see :ref:`Mackay and
Denniston <Mackay2>` for full details). In order to calculate :math:`m_u`,
the fluid density is interpolated to the MD particle location, and
multiplied by a volume, node_area * :math:`dx_{LB}`, where node_area
represents the portion of the surface area of the composite object
associated with a given MD particle. By default, node_area is set
equal to :math:`dx_{LB}^2`; however specific values for given atom types
can be set using the *setArea* keyword.
The user also has the option of specifying their own value for the
force coupling constant, for all the MD particles associated with the
fix, through the use of the *setGamma* keyword. This may be useful
when modelling porous particles. See :ref:`Mackay et al. <fluid-Mackay>` for a
detailed description of the method by which the user can choose an
appropriate :math:`\gamma` value.
representative fluid mass at the particle location, and :math:`\Delta t`
is the time step. The fluid mass :math:`m_u` that the MD particle
interacts with is calculated internally. This coupling is chosen to
constrain the particle and associated fluid velocity to match at the end
of the time step. As with other constraints, such as :doc:`shake
<fix_shake>`, this constraint can remove degrees of freedom from the
simulation which are accounted for internally in the algorithm.
.. note::
while this fix applies the force of the particles on the fluid,
it does not apply the force of the fluid to the particles. When the
force coupling constant is set using the default method, there is only
one option to include this hydrodynamic force on the particles, and
that is through the use of the :doc:`lb/viscous <fix_lb_viscous>` fix.
This fix adds the hydrodynamic force to the total force acting on the
particles, after which any of the built-in LAMMPS integrators can be
used to integrate the particle motion. However, if the user specifies
their own value for the force coupling constant, as mentioned in
:ref:`Mackay et al. <fluid-Mackay>`, the built-in LAMMPS integrators may prove to
be unstable. Therefore, we have included our own integrators
:doc:`fix lb/rigid/pc/sphere <fix_lb_rigid_pc_sphere>`, and
:doc:`fix lb/pc <fix_lb_pc>`, to solve for the particle motion in these
cases. These integrators should not be used with the
:doc:`lb/viscous <fix_lb_viscous>` fix, as they add hydrodynamic forces
to the particles directly. In addition, they can not be used if the
force coupling constant has been set the default way.
.. note::
if the force coupling constant is set using the default method,
and the :doc:`lb/viscous <fix_lb_viscous>` fix is NOT used to add the
While this fix applies the force of the particles on the fluid, it
does not apply the force of the fluid to the particles. There is
only one option to include this hydrodynamic force on the particles,
and that is through the use of the :doc:`lb/viscous <fix_lb_viscous>`
fix. This fix adds the hydrodynamic force to the total force acting
on the particles, after which any of the built-in LAMMPS integrators
can be used to integrate the particle motion. If the
:doc:`lb/viscous <fix_lb_viscous>` fix is NOT used to add the
hydrodynamic force to the total force acting on the particles, this
physically corresponds to a situation in which an infinitely massive
particle is moving through the fluid (since collisions between the
particle and the fluid do not act to change the particle's velocity).
Therefore, the user should set the mass of the particle to be
significantly larger than the mass of the fluid at the particle
location, in order to approximate an infinitely massive particle (see
the dragforce test run for an example).
In this case, setting *scaleGamma* to -1 for the corresponding
particle type will explicitly take this limit (of infinite particle
mass) in computing the force coupling for the fluid force.
----------
Inside the fix, parameters are scaled by the lattice-Boltzmann
Physical parameters describing the fluid are specified through
*viscosity* and *density*. These parameters should all be given in
terms of the mass, distance, and time units chosen for the main LAMMPS
run, as they are scaled by the LB timestep, lattice spacing, and mass
unit, inside the fix.
The *dx* keyword allows the user to specify a value for the LB grid
spacing and the *dm* keyword allows the user to specify the LB mass
unit. Inside the fix, parameters are scaled by the lattice-Boltzmann
timestep, :math:`dt_{LB}`, grid spacing, :math:`dx_{LB}`, and mass unit,
:math:`dm_{LB}`. :math:`dt_{LB}` is set equal to
:math:`\mathrm{nevery}\cdot dt_{MD}`, where :math:`dt_{MD}` is the MD timestep.
By default,
:math:`dm_{LB}` is set equal to 1.0, and :math:`dx_{LB}` is chosen so that
:math:`\frac{\tau}{dt} = \frac{3\eta dt}{\rho dx^2}` is approximately equal to 1.
However, the user has the option of specifying their own values for
:math:`dm_{LB}`, and :math:`dx_{LB}`, by using
the optional keywords *dm*, and *dx* respectively.
:math:`\mathrm{nevery}\cdot dt_{MD}`, where :math:`dt_{MD}` is the MD
timestep. By default, :math:`dm_{LB}` is set equal to 1.0, and
:math:`dx_{LB}` is chosen so that :math:`\frac{\tau}{dt} = \frac{3\eta
dt}{\rho dx^2}` is approximately equal to 1.
.. note::
@ -223,74 +202,27 @@ the optional keywords *dm*, and *dx* respectively.
with equal lengths in all dimensions, and the default value for
:math:`dx_{LB}` is used, this will automatically be satisfied.
Physical parameters describing the fluid are specified through
*viscosity*, *density*, and *a0*\ . If the force coupling constant is
set the default way, the surface area associated with the MD particles
is specified using the *setArea* keyword. If the user chooses to
specify a value for the force coupling constant, this is set using the
*setGamma* keyword. These parameters should all be given in terms of
the mass, distance, and time units chosen for the main LAMMPS run, as
they are scaled by the LB timestep, lattice spacing, and mass unit,
inside the fix.
----------
The *setArea* keyword allows the user to associate a surface area with
a given atom type. For example if a spherical composite object of
radius R is represented as a spherical shell of N evenly distributed
MD particles, all of the same type, the surface area per particle
associated with that atom type should be set equal to :math:`\frac{4\pi R^2}{N}`.
This keyword should only be used if the force coupling constant,
:math:`\gamma`, is set the default way.
The *setGamma* keyword allows the user to specify their own value for
the force coupling constant, :math:`\gamma`, instead of using the default
value.
The *scaleGamma* keyword should be used in conjunction with the
*setGamma* keyword, when the user wishes to specify different :math:`\gamma`
values for different atom types. This keyword allows the user to
scale the *setGamma* :math:`\gamma` value by a factor, gammaFactor,
for a given atom type.
The *dx* keyword allows the user to specify a value for the LB grid
spacing.
The *dm* keyword allows the user to specify the LB mass unit.
If the *a0* keyword is used, the value specified is used for the
square of the speed of sound in the fluid. If this keyword is not
present, the speed of sound squared is set equal to
:math:`\frac{1}{3}\left(\frac{dx_{LB}}{dt_{LB}}\right)^2`.
Setting :math:`a0 > (\frac{dx_{LB}}{dt_{LB}})^2` is not allowed,
as this may lead to instabilities.
If the *noise* keyword is used, followed by a positive temperature
value, and a positive integer random number seed, a thermal
lattice-Boltzmann algorithm is used. If *LBtype* is set equal to 1
(i.e. the standard LB integrator is chosen), the thermal LB algorithm
of :ref:`Adhikari et al. <Adhikari>` is used; however if *LBtype* is set
equal to 2 both the LB integrator, and thermal LB algorithm described
in :ref:`Ollila et al. <Ollila>` are used.
value, and a positive integer random number seed, the thermal LB algorithm
of :ref:`Adhikari et al. <Adhikari>` is used.
If the *calcforce* keyword is used, both the fluid force and torque
acting on the specified particle group are printed to the screen every
N timesteps.
If the keyword *stencil* is used, the value sets the number of
interpolation points used in each direction. For this, the user has the
choice between a trilinear stencil (*stencil* 2), which provides a
support of 8 lattice sites, or the 3-point immersed boundary method
stencil (*stencil* 3), which provides a support of 27 lattice sites, or
the 4-point Keys' interpolation stencil (stencil 4), which provides a
support of 64 lattice sites. The trilinear stencil is the default as it
is better suited for simulation of objects close to walls or other
objects, due to its smaller support. The 3-point stencil provides
smoother motion of the lattice and is suitable for particles not likely
to be to close to walls or other objects.
If the keyword *trilinear* is used, the trilinear stencil is used to
interpolate the particle nodes onto the fluid mesh. By default, the
immersed boundary method, Peskin stencil is used. Both of these
interpolation methods are described in :ref:`Mackay et al. <fluid-Mackay>`.
If the keyword *D3Q19* is used, the 19 velocity (D3Q19) lattice is
used by the lattice-Boltzmann algorithm. By default, the 15 velocity
(D3Q15) lattice is used.
If the keyword *write_restart* is used, followed by a positive
integer, N, a binary restart file is printed every N LB timesteps.
This restart file only contains information about the fluid.
Therefore, a LAMMPS restart file should also be written in order to
print out full details of the simulation.
If the keyword *write_restart* is used, followed by a positive integer,
N, a binary restart file is printed every N LB timesteps. This restart
file only contains information about the fluid. Therefore, a LAMMPS
restart file should also be written in order to print out full details
of the simulation.
.. note::
@ -308,19 +240,100 @@ conditions in the z-direction. If fixed boundary conditions are
present in the z-direction, and this keyword is not used, the walls
are assumed to be stationary.
If the *pressurebcx* keyword is used, a pressure jump (implemented by a
step jump in density) is imposed at the (periodic) x-boundary. The
value set specifies what would be the resulting equilibrium average
pressure gradient in the x-direction if the system had a constant
cross-section (i.e. resistance to flow). It is converted to a pressure
jump by multiplication by the system size in the x-direction. As this
value should normally be quite small, it is also assumed to be scaled
by 1000.
If the *bodyforce* keyword is used, a constant body force is added to
the fluid, defined by it's x, y and z components.
If the *printfluid* keyword is used, followed by a positive integer, N,
the fluid densities and velocities at each lattice site are printed to the
screen every N timesteps.
If the keyword *D3Q19* is used, the 19 velocity (D3Q19) lattice is
used by the lattice-Boltzmann algorithm. By default, the 15 velocity
(D3Q15) lattice is used.
If the *dumpxdmf* keyword is used, followed by a positive integer, N,
and a file name, the fluid densities and velocities at each lattice site
are output to an xdmf file every N timesteps. This is a binary file
format that can be read by visualization packages such as `Paraview
<https://www.paraview.org/>`_ . The xdmf file format contains a time
index for each frame dump and the value timeI = 1 uses simulation time
while 0 uses the output frame number to index xdmf file. The later can
be useful if the :doc:`dump vtk <dump_vtk>` command is used to output
the particle positions at the same timesteps and you want to visualize
both the fluid and particle data together in `Paraview
<https://www.paraview.org/>`_ .
The *scaleGamma* keyword allows the user to scale the :math:`\gamma`
value by a factor, gammaFactor, for a given atom type. Setting
*scaleGamma* to -1 for the corresponding particle type will explicitly
take the limit of infinite particle mass in computing the force coupling
for the fluid force (see note above).
If the *a0* keyword is used, the value specified is used for the square
of the speed of sound in the fluid. If this keyword is not present, the
speed of sound squared is set equal to
:math:`\frac{1}{3}\left(\frac{dx_{LB}}{dt_{LB}}\right)^2`. Setting
:math:`a0 > (\frac{dx_{LB}}{dt_{LB}})^2` is not allowed, as this may
lead to instabilities. As the speed of sound should usually be much
larger than any fluid velocity of interest, its value does not normally
have a significant impact on the results. As such, it is usually best
to use the default for this option.
The *npits* keyword (followed by integer arguments: npits, h_p, l_p,
l_pp, l_e) sets the fluid domain to the pits geometry. These arguments
should only be used if you actually want something more complex than a
rectangular/cubic geometry. The npits value sets the number of pits
regions (arranged along x). The remaining arguments are sizes measured
in multiples of dx_lb: h_p is the z-height of the pit regions, l_p is
the x-length of the pit regions, l_pp is the length of the region
between consecutive pits (referred to as a "slit" region), and l_e is
the x-length of the slit regions at each end of the channel. The pit
geometry must fill the system in the x-direction but can be longer, in
which case it is truncated (which enables asymmetric entrance/exit end
sections). The additional *wp* keyword allows the width (in
y-direction) of the pit to be specified (the default is full width) and
the *sw* keyword indicates that there should be sidewalls in the
y-direction (default is periodic in y-direction). These parameters are
illustrated below::
Sideview (in xz plane) of pit geometry:
______________________________________________________________________
slit slit slit ^
|
<---le---><---------lp-------><---lpp---><-------lp--------><---le---> hs = (Nbz-1) - hp
|
__________ __________ __________ v
| | | | ^ z
| | | | | |
| pit | | pit | hp +-x
| | | | |
|__________________| |__________________| v
Endview (in yz plane) of pit geometry (no sw so wp is active):
_____________________
^
|
hs
|
_____________________ v
| | ^
| | | z
|<---wp--->| hp |
| | | +-y
|__________| v
----------
For further details, as well as descriptions and results of several
test runs, see :ref:`Mackay et al. <fluid-Mackay>`. Please include a citation to
this paper if the lb_fluid fix is used in work contributing to
published research.
For further details, as well as descriptions and results of several test
runs, see :ref:`Denniston et al. <fluid-Denniston>`. Please include a
citation to this paper if the lb_fluid fix is used in work contributing
to published research.
----------
@ -333,68 +346,77 @@ binary restart files, if requested, independent of the main LAMMPS
is written to the main LAMMPS :doc:`binary restart files <restart>`.
None of the :doc:`fix_modify <fix_modify>` options are relevant to this
fix. No global or per-atom quantities are stored by this fix for
access by various :doc:`output commands <Howto_output>`. No parameter
of this fix can be used with the *start/stop* keywords of the
:doc:`run <run>` command. This fix is not invoked during :doc:`energy minimization <minimize>`.
fix.
The fix computes a global scalar which can be accessed by various
:doc:`output commands <Howto_output>`. The scalar is the current
temperature of the group of particles described by *group-ID* along with
the fluid constrained to move with them. The temperature is computed via
the kinetic energy of the group and fluid constrained to move with them
and the total number of degrees of freedom (calculated internally). If
the particles are not integrated independently (such as via :doc:`fix
NVE <fix_nve>`) but have additional constraints imposed on them (such as
via integration using :doc:`fix rigid <fix_rigid>`) the degrees of
freedom removed from these additional constraints will not be properly
accounted for. In this case, the user can specify the total degrees of
freedom independently using the *dof* keyword.
The fix also computes a global array of values which can be accessed by
various :doc:`output commands <Howto_output>`. There are 5 entries in
the array. The first entry is the temperature of the fluid, the second
entry is the total mass of the fluid plus particles, the third through
fifth entries give the x, y, and z total momentum of the fluid plus
particles.
No parameter of this fix can be used with the *start/stop* keywords of
the :doc:`run <run>` command. This fix is not invoked during
:doc:`energy minimization <minimize>`.
Restrictions
""""""""""""
This fix is part of the LATBOLTZ package. It is only enabled if LAMMPS
was built with that package. See the :doc:`Build package <Build_package>` page for more info.
was built with that package. See the :doc:`Build package
<Build_package>` page for more info.
This fix can only be used with an orthogonal simulation domain.
Walls have only been implemented in the z-direction. Therefore, the
boundary conditions, as specified via the main LAMMPS boundary command
must be periodic for x and y, and either fixed or periodic for z.
Shrink-wrapped boundary conditions are not permitted with this fix.
The boundary conditions for the fluid are specified independently to the
particles. However, these should normally be specified consistently via
the main LAMMPS :doc:`boundary <boundary>` command (p p p, p p f, and p
f f are the only consistent possibilities). Shrink-wrapped boundary
conditions are not permitted with this fix.
This fix must be used before any of :doc:`fix lb/viscous <fix_lb_viscous>`, :doc:`fix lb/momentum <fix_lb_momentum>`, :doc:`fix lb/rigid/pc/sphere <fix_lb_rigid_pc_sphere>`, and/ or :doc:`fix lb/pc <fix_lb_pc>` , as the fluid needs to be initialized before
any of these routines try to access its properties. In addition, in
order for the hydrodynamic forces to be added to the particles, this
fix must be used in conjunction with the
:doc:`lb/viscous <fix_lb_viscous>` fix if the force coupling constant is
set by default, or either the :doc:`lb/viscous <fix_lb_viscous>` fix or
one of the :doc:`lb/rigid/pc/sphere <fix_lb_rigid_pc_sphere>` or
:doc:`lb/pc <fix_lb_pc>` integrators, if the user chooses to specify
their own value for the force coupling constant.
This fix must be used before any of :doc:`fix lb/viscous
<fix_lb_viscous>` and :doc:`fix lb/momentum <fix_lb_momentum>` as the
fluid needs to be initialized before any of these routines try to access
its properties. In addition, in order for the hydrodynamic forces to be
added to the particles, this fix must be used in conjunction with the
:doc:`lb/viscous <fix_lb_viscous>` fix.
This fix needs to be used in conjunction with a standard LAMMPS
integrator such as :doc:`fix NVE <fix_nve>` or :doc:`fix rigid
<fix_rigid>`.
Related commands
""""""""""""""""
:doc:`fix lb/viscous <fix_lb_viscous>`, :doc:`fix lb/momentum <fix_lb_momentum>`, :doc:`fix lb/rigid/pc/sphere <fix_lb_rigid_pc_sphere>`, :doc:`fix lb/pc <fix_lb_pc>`
:doc:`fix lb/viscous <fix_lb_viscous>`, :doc:`fix lb/momentum <fix_lb_momentum>`
Default
"""""""
By default, the force coupling constant is set according to
.. math::
\gamma = \frac{2m_um_v}{m_u+m_v}\left(\frac{1}{\Delta t_{collision}}\right)
and an area of :math:`dx_{LB}^2` per node, used to calculate the fluid mass at
the particle node location, is assumed.
*dx* is chosen such that :math:`\frac{\tau}{dt_{LB}} =
\frac{3\eta dt_{LB}}{\rho dx_{LB}^2}` is approximately equal to 1.
*dx* is chosen such that :math:`\frac{\tau}{dt_{LB}} = \frac{3\eta dt_{LB}}{\rho dx_{LB}^2}` is approximately equal to 1.
*dm* is set equal to 1.0.
*a0* is set equal to :math:`\frac{1}{3}\left(\frac{dx_{LB}}{dt_{LB}}\right)^2`.
The Peskin stencil is used as the default interpolation method.
The trilinear stencil is used as the default interpolation method.
The D3Q15 lattice is used for the lattice-Boltzmann algorithm.
If walls are present, they are assumed to be stationary.
----------
.. _Ollila:
.. _fluid-Denniston:
**(Ollila et al.)** Ollila, S.T.T., Denniston, C., Karttunen, M., and Ala-Nissila, T., Fluctuating lattice-Boltzmann model for complex fluids, J. Chem. Phys. 134 (2011) 064902.
.. _fluid-Mackay:
**(Mackay et al.)** Mackay, F. E., Ollila, S.T.T., and Denniston, C., Hydrodynamic Forces Implemented into LAMMPS through a lattice-Boltzmann fluid, Computer Physics Communications 184 (2013) 2021-2031.
**(Denniston et al.)** Denniston, C., Afrasiabian, N., Cole-Andre, M.G., Mackay, F. E., Ollila, S.T.T., and Whitehead, T., LAMMPS lb/fluid fix version 2: Improved Hydrodynamic Forces Implemented into LAMMPS through a lattice-Boltzmann fluid, Computer Physics Communications 275 (2022) `108318 <https://doi.org/10.1016/j.cpc.2022.108318>`_ .
.. _Mackay2:
@ -403,3 +425,4 @@ If walls are present, they are assumed to be stationary.
.. _Adhikari:
**(Adhikari et al.)** Adhikari, R., Stratford, K., Cates, M. E., and Wagner, A. J., Fluctuating lattice Boltzmann, Europhys. Lett. 71 (2005) 473-479.

2
doc/src/fix_lb_momentum.rst
View File

@ -38,7 +38,7 @@ lattice-Boltzmann fluid is present.
Zero the total linear momentum of the system, including both the atoms
specified by group-ID and the lattice-Boltzmann fluid every nevery
timesteps. This is accomplished by adjusting the particle velocities
timesteps. If there are no atoms specified by group-ID only the fluid momentum is affected. This is accomplished by adjusting the particle velocities
and the fluid velocities at each lattice site.
.. note::

65
doc/src/fix_lb_pc.rst
View File

@ -1,65 +0,0 @@
.. index:: fix lb/pc
fix lb/pc command
=================
Syntax
""""""
.. parsed-literal::
fix ID group-ID lb/pc
* ID, group-ID are documented in the :doc:`fix <fix>` command
* lb/pc = style name of this fix command
Examples
""""""""
.. code-block:: LAMMPS
fix 1 all lb/pc
Description
"""""""""""
Update the positions and velocities of the individual particles
described by *group-ID*, experiencing velocity-dependent hydrodynamic
forces, using the integration algorithm described in :ref:`Mackay et al. <Mackay1>`. This integration algorithm should only be used if a
user-specified value for the force-coupling constant used in :doc:`fix lb/fluid <fix_lb_fluid>` has been set; do not use this integration
algorithm if the force coupling constant has been set by default.
Restart, fix_modify, output, run start/stop, minimize info
"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""
No information about this fix is written to :doc:`binary restart files <restart>`. None of the :doc:`fix_modify <fix_modify>` options
are relevant to this fix. No global or per-atom quantities are stored
by this fix for access by various :doc:`output commands <Howto_output>`.
No parameter of this fix can be used with the *start/stop* keywords of
the :doc:`run <run>` command. This fix is not invoked during :doc:`energy minimization <minimize>`.
Restrictions
""""""""""""
This fix is part of the LATBOLTZ package. It is only enabled if LAMMPS
was built with that package. See the :doc:`Build package <Build_package>` page for more info.
Can only be used if a lattice-Boltzmann fluid has been created via the
:doc:`fix lb/fluid <fix_lb_fluid>` command, and must come after this
command.
Related commands
""""""""""""""""
:doc:`fix lb/fluid <fix_lb_fluid>` :doc:`fix lb/rigid/pc/sphere <fix_lb_rigid_pc_sphere>`
Default
"""""""
none.
----------
.. _Mackay1:
**(Mackay et al.)** Mackay, F. E., Ollila, S.T.T., and Denniston, C., Hydrodynamic Forces Implemented into LAMMPS through a lattice-Boltzmann fluid, Computer Physics Communications 184 (2013) 2021-2031.

167
doc/src/fix_lb_rigid_pc_sphere.rst
View File

@ -1,167 +0,0 @@
.. index:: fix lb/rigid/pc/sphere
fix lb/rigid/pc/sphere command
==============================
Syntax
""""""
.. parsed-literal::
fix ID group-ID lb/rigid/pc/sphere bodystyle args keyword values ...
* ID, group-ID are documented in :doc:`fix <fix>` command
* lb/rigid/pc/sphere = style name of this fix command
* bodystyle = *single* or *molecule* or *group*
.. parsed-literal::
*single* args = none
*molecule* args = none
*group* args = N groupID1 groupID2 ...
N = # of groups
* zero or more keyword/value pairs may be appended
* keyword = *force* or *torque* or *innerNodes*
.. parsed-literal::
*force* values = M xflag yflag zflag
M = which rigid body from 1-Nbody (see asterisk form below)
xflag,yflag,zflag = off/on if component of center-of-mass force is active
*torque* values = M xflag yflag zflag
M = which rigid body from 1-Nbody (see asterisk form below)
xflag,yflag,zflag = off/on if component of center-of-mass torque is active
*innerNodes* values = innergroup-ID
innergroup-ID = ID of the atom group which does not experience a hydrodynamic force from the lattice-Boltzmann fluid
Examples
""""""""
.. code-block:: LAMMPS
fix 1 spheres lb/rigid/pc/sphere
fix 1 all lb/rigid/pc/sphere force 1 0 0 innerNodes ForceAtoms
Description
"""""""""""
This fix is based on the :doc:`fix rigid <fix_rigid>` command, and was
created to be used in place of that fix, to integrate the equations of
motion of spherical rigid bodies when a lattice-Boltzmann fluid is
present with a user-specified value of the force-coupling constant.
The fix uses the integration algorithm described in :ref:`Mackay et
al. <Mackay>` to update the positions, velocities, and orientations of
a set of spherical rigid bodies experiencing velocity dependent
hydrodynamic forces. The spherical bodies are assumed to rotate as
solid, uniform density spheres, with moments of inertia calculated
using the combined sum of the masses of all the constituent particles
(which are assumed to be point particles).
----------
By default, all of the atoms that this fix acts on experience a
hydrodynamic force due to the presence of the lattice-Boltzmann fluid.
However, the *innerNodes* keyword allows the user to specify atoms
belonging to a rigid object which do not interact with the
lattice-Boltzmann fluid (i.e. these atoms do not feel a hydrodynamic
force from the lattice-Boltzmann fluid). This can be used to
distinguish between atoms on the surface of a non-porous object, and
those on the inside.
This feature can be used, for example, when implementing a hard sphere
interaction between two spherical objects. Instead of interactions
occurring between the particles on the surfaces of the two spheres, it
is desirable simply to place an atom at the center of each sphere,
which does not contribute to the hydrodynamic force, and have these
central atoms interact with one another.
----------
Apart from the features described above, this fix is very similar to
the rigid fix (although it includes fewer optional arguments, and
assumes the constituent atoms are point particles); see
:doc:`fix rigid <fix_rigid>` for a complete documentation.
Restart, fix_modify, output, run start/stop, minimize info
"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""
No information about the *rigid* and *rigid/nve* fixes are written to
:doc:`binary restart files <restart>`.
The :doc:`fix_modify <fix_modify>` *virial* option is supported by
this fix to add the contribution due to the added forces on atoms to
both the global pressure and per-atom stress of the system via the
:doc:`compute pressure <compute_pressure>` and :doc:`compute
stress/atom <compute_stress_atom>` commands. The former can be
accessed by :doc:`thermodynamic output <thermo_style>`. The default
setting for this fix is :doc:`fix_modify virial yes <fix_modify>`.
Similar to the :doc:`fix rigid <fix_rigid>` command: The rigid fix
computes a global scalar which can be accessed by various :doc:`output
commands <Howto_output>`. The scalar value calculated by these fixes
is "intensive". The scalar is the current temperature of the
collection of rigid bodies. This is averaged over all rigid bodies
and their translational and rotational degrees of freedom. The
translational energy of a rigid body is 1/2 m v\^2, where m = total
mass of the body and v = the velocity of its center of mass. The
rotational energy of a rigid body is 1/2 I w\^2, where I = the moment
of inertia tensor of the body and w = its angular velocity. Degrees
of freedom constrained by the *force* and *torque* keywords are
removed from this calculation.
All of these fixes compute a global array of values which can be
accessed by various :doc:`output commands <Howto_output>`. The number
of rows in the array is equal to the number of rigid bodies. The
number of columns is 15. Thus for each rigid body, 15 values are
stored: the xyz coords of the center of mass (COM), the xyz components
of the COM velocity, the xyz components of the force acting on the
COM, the xyz components of the torque acting on the COM, and the xyz
image flags of the COM, which have the same meaning as image flags for
atom positions (see the "dump" command). The force and torque values
in the array are not affected by the *force* and *torque* keywords in
the fix rigid command; they reflect values before any changes are made
by those keywords.
The ordering of the rigid bodies (by row in the array) is as follows.
For the *single* keyword there is just one rigid body. For the
*molecule* keyword, the bodies are ordered by ascending molecule ID.
For the *group* keyword, the list of group IDs determines the ordering
of bodies.
The array values calculated by these fixes are "intensive", meaning
they are independent of the number of atoms in the simulation.
No parameter of these fixes can be used with the *start/stop* keywords
of the :doc:`run <run>` command. These fixes are not invoked during
:doc:`energy minimization <minimize>`.
Restrictions
""""""""""""
This fix is part of the LATBOLTZ package. It is only enabled if LAMMPS
was built with that package. See the :doc:`Build package
<Build_package>` page for more info.
Can only be used if a lattice-Boltzmann fluid has been created via the
:doc:`fix lb/fluid <fix_lb_fluid>` command, and must come after this
command. Should only be used if the force coupling constant used in
:doc:`fix lb/fluid <fix_lb_fluid>` has been set by the user; this
integration fix cannot be used if the force coupling constant is set
by default.
Related commands
""""""""""""""""
:doc:`fix lb/fluid <fix_lb_fluid>`, :doc:`fix lb/pc <fix_lb_pc>`
Default
"""""""
The defaults are force \* on on on, and torque \* on on on.
----------
.. _Mackay:
**(Mackay et al.)** Mackay, F. E., Ollila, S.T.T., and Denniston, C., Hydrodynamic Forces Implemented into LAMMPS through a lattice-Boltzmann fluid, Computer Physics Communications 184 (2013) 2021-2031.

30
doc/src/fix_lb_viscous.rst
View File

@ -25,27 +25,14 @@ Description
This fix is similar to the :doc:`fix viscous <fix_viscous>` command, and
is to be used in place of that command when a lattice-Boltzmann fluid
is present, and the user wishes to integrate the particle motion using
one of the built in LAMMPS integrators.
is present using the :doc:`fix lb/fluid <fix_lb_fluid>`. This should be used in conjunction with one of the built-in LAMMPS integrators, such as :doc:`fix NVE <fix_nve>` or :doc:`fix rigid <fix_rigid>`.
This fix adds a force, F = - Gamma\*(velocity-fluid_velocity), to each
atom, where Gamma is the force coupling constant described in the :doc:`fix lb/fluid <fix_lb_fluid>` command (which applies an equal and
opposite force to the fluid).
.. note::
This fix should only be used in conjunction with one of the
built in LAMMPS integrators; it should not be used with the :doc:`fix lb/pc <fix_lb_pc>` or :doc:`fix lb/rigid/pc/sphere <fix_lb_rigid_pc_sphere>` integrators, which
already include the hydrodynamic forces. These latter fixes should
only be used if the force coupling constant has been set by the user
(instead of using the default value); if the default force coupling
value is used, then this fix provides the only method for adding the
hydrodynamic forces to the particles.
This fix adds a viscous force to each atom to cause it move with the same velocity as the fluid (an equal and opposite force is applied to the fluid via :doc:`fix lb/fluid <fix_lb_fluid>`). When :doc:`fix lb/fluid <fix_lb_fluid>` is called with the noise option, the atoms will also experience random forces which will thermalize them to the same temperature as the fluid. In this way, the combination of this fix with :doc:`fix lb/fluid <fix_lb_fluid>` and a LAMMPS integrator like :doc:`fix NVE <fix_nve>` is analogous to :doc:`fix langevin <fix_langevin>` except here the fluid is explicit. The temperature of the particles can be monitored via the scalar output of :doc:`fix lb/fluid <fix_lb_fluid>`.
----------
For further details, as well as descriptions and results of several
test runs, see :ref:`Mackay et al. <Mackay3>`. Please include a citation to
For details of this fix, as well as descriptions and results of several
test runs, see :ref:`Denniston et al. <fluid-Denniston2>`. Please include a citation to
this paper if this fix is used in work contributing to published
research.
@ -78,14 +65,11 @@ Can only be used if a lattice-Boltzmann fluid has been created via the
:doc:`fix lb/fluid <fix_lb_fluid>` command, and must come after this
command.
This fix should not be used if either the :doc:`fix lb/pc <fix_lb_pc>`
or :doc:`fix lb/rigid/pc/sphere <fix_lb_rigid_pc_sphere>` integrator is
used.
Related commands
""""""""""""""""
:doc:`fix lb/fluid <fix_lb_fluid>`, :doc:`fix lb/pc <fix_lb_pc>`, :doc:`fix lb/rigid/pc/sphere <fix_lb_rigid_pc_sphere>`
:doc:`fix lb/fluid <fix_lb_fluid>`
Default
"""""""
@ -94,6 +78,6 @@ none
----------
.. _Mackay3:
.. _fluid-Denniston2:
**(Mackay et al.)** Mackay, F. E., Ollila, S.T.T., and Denniston, C., Hydrodynamic Forces Implemented into LAMMPS through a lattice-Boltzmann fluid, Computer Physics Communications 184 (2013) 2021-2031.
**(Denniston et al.)** Denniston, C., Afrasiabian, N., Cole-Andre, M.G., Mackay, F. E., Ollila, S.T.T., and Whitehead, T., LAMMPS lb/fluid fix version 2: Improved Hydrodynamic Forces Implemented into LAMMPS through a lattice-Boltzmann fluid, Computer Physics Communications 275 (2022) `108318 <https://doi.org/10.1016/j.cpc.2022.108318>`_ .

23
doc/src/fix_numdiff.rst
View File

@ -13,16 +13,15 @@ Syntax
* ID, group-ID are documented in :doc:`fix <fix>` command
* numdiff = style name of this fix command
* Nevery = calculate force by finite difference every this many timesteps
* delta = finite difference displacement length (distance units)
* delta = size of atom displacements (distance units)
Examples
""""""""
.. code-block:: LAMMPS
fix 1 all numdiff 1 0.0001
fix 1 all numdiff 10 1e-6
fix 1 all numdiff 100 0.01
fix 1 movegroup numdiff 100 0.01
Description
"""""""""""
@ -67,16 +66,17 @@ by two times *delta*.
The cost of each energy evaluation is essentially the cost of an MD
timestep. Thus invoking this fix once for a 3d system has a cost
of 6N timesteps, where N is the total number of atoms in the system
(assuming all atoms are included in the group). So this fix can be
very expensive to use for large systems.
of 6N timesteps, where N is the total number of atoms in the system.
So this fix can be very expensive to use for large systems.
One expedient alternative is to define the fix for a group containing
only a few atoms.
----------
The *Nevery* argument specifies on what timesteps the force will
be used calculated by finite difference.
The *delta* argument specifies the positional displacement each
The *delta* argument specifies the size of the displacement each
atom will undergo.
----------
@ -93,7 +93,12 @@ This fix produces a per-atom array which can be accessed by various
the force on each atom as calculated by finite difference. The
per-atom values can only be accessed on timesteps that are multiples
of *Nevery* since that is when the finite difference forces are
calculated.
calculated. See the examples in *examples/numdiff* directory
to see how this fix can be used to directly compare with
the analytic forces computed by LAMMPS.
The array values calculated by this compute
will be in force :doc:`units <units>`.
No parameter of this fix can be used with the *start/stop* keywords of
the :doc:`run <run>` command. This fix is invoked during :doc:`energy
@ -108,7 +113,7 @@ was built with that package. See the :doc:`Build package <Build_package>` page
Related commands
""""""""""""""""
:doc:`dynamical_matrix <dynamical_matrix>`,
:doc:`dynamical_matrix <dynamical_matrix>`, :doc:`fix numdiff/virial <fix_numdiff_virial>`,
Default
"""""""

115
doc/src/fix_numdiff_virial.rst Normal file
View File

@ -0,0 +1,115 @@
.. index:: fix numdiff/virial
fix numdiff/virial command
==========================
Syntax
""""""
.. parsed-literal::
fix ID group-ID numdiff/virial Nevery delta
* ID, group-ID are documented in :doc:`fix <fix>` command
* numdiff/virial = style name of this fix command
* Nevery = calculate virial by finite difference every this many timesteps
* delta = magnitude of strain fields (dimensionless)
Examples
""""""""
.. code-block:: LAMMPS
fix 1 all numdiff/stress 10 1e-6
Description
"""""""""""
Calculate the virial stress tensor through a finite difference calculation of
energy versus strain. These values can be compared to the analytic virial
tensor computed by pair styles, bond styles, etc. This can be useful for
debugging or other purposes. The specified group must be "all".
This fix applies linear strain fields of magnitude *delta* to all the
atoms relative to a point at the center of the box. The
strain fields are in six different directions, corresponding to the
six Cartesian components of the stress tensor defined by LAMMPS.
For each direction it applies the strain field in both the positive
and negative senses, and the new energy of the entire system
is calculated after each. The difference in these two energies
divided by two times *delta*, approximates the corresponding
component of the virial stress tensor, after applying
a suitable unit conversion.
.. note::
It is important to choose a suitable value for delta, the magnitude of
strains that are used to generate finite difference
approximations to the exact virial stress. For typical systems, a value in
the range of 1 part in 1e5 to 1e6 will be sufficient.
However, the best value will depend on a multitude of factors
including the stiffness of the interatomic potential, the thermodynamic
state of the material being probed, and so on. The only way to be sure
that you have made a good choice is to do a sensitivity study on a
representative atomic configuration, sweeping over a wide range of
values of delta. If delta is too small, the output values will vary
erratically due to truncation effects. If delta is increased beyond a
certain point, the output values will start to vary smoothly with
delta, due to growing contributions from higher order derivatives. In
between these two limits, the numerical virial values should be largely
independent of delta.
----------
The *Nevery* argument specifies on what timesteps the force will
be used calculated by finite difference.
The *delta* argument specifies the size of the displacement each
atom will undergo.
----------
Restart, fix_modify, output, run start/stop, minimize info
"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""
No information about this fix is written to :doc:`binary restart files
<restart>`. None of the :doc:`fix_modify <fix_modify>` options are
relevant to this fix.
This fix produces a global vector which can be accessed by various
:doc:`output commands <Howto_output>`, which stores the components of
the virial stress tensor as calculated by finite difference. The
global vector can only be accessed on timesteps that are multiples
of *Nevery* since that is when the finite difference virial is
calculated. See the examples in *examples/numdiff* directory
to see how this fix can be used to directly compare with
the analytic virial stress tensor computed by LAMMPS.
The order of the virial stress tensor components is *xx*, *yy*, *zz*,
*yz*, *xz*, and *xy*, consistent with Voigt notation. Note that
the vector produced by :doc:`compute pressure <compute_pressure>`
uses a different ordering, with *yz* and *xy* swapped.
The vector values calculated by this compute are
"intensive". The vector values will be in pressure
:doc:`units <units>`.
No parameter of this fix can be used with the *start/stop* keywords of
the :doc:`run <run>` command. This fix is invoked during :doc:`energy
minimization <minimize>`.
Restrictions
""""""""""""
This fix is part of the EXTRA-FIX package. It is only enabled if LAMMPS
was built with that package. See the :doc:`Build package <Build_package>` page for more info.
Related commands
""""""""""""""""
:doc:`fix numdiff <fix_numdiff>`, :doc:`compute pressure <compute_pressure>`
Default
"""""""
none

9
doc/src/fix_nvt_sllod.rst
View File

@ -66,7 +66,10 @@ equivalent to Newton's equations of motion for shear flow by
:ref:`(Evans and Morriss) <Evans3>`. They were later shown to generate
the desired velocity gradient and the correct production of work by
stresses for all forms of homogeneous flow by :ref:`(Daivis and Todd)
<Daivis>`. As implemented in LAMMPS, they are coupled to a
<Daivis>`.
The LAMMPS implementation corresponds to the p-SLLOD variant
of SLLOD. :ref:`(Edwards) <Edwards>`.
The equations of motion are coupled to a
Nose/Hoover chain thermostat in a velocity Verlet formulation, closely
following the implementation used for the :doc:`fix nvt <fix_nh>`
command.
@ -180,6 +183,10 @@ Same as :doc:`fix nvt <fix_nh>`, except tchain = 1.
**(Daivis and Todd)** Daivis and Todd, J Chem Phys, 124, 194103 (2006).
.. _Edwards:
**(Edwards)** Edwards, Baig, and Keffer, J Chem Phys 124, 194104 (2006).
.. _Daivis-sllod:
**(Daivis and Todd)** Daivis and Todd, Nonequilibrium Molecular Dynamics (book),

2
doc/src/fix_oneway.rst
View File

@ -51,7 +51,7 @@ the :doc:`run <run>` command. This fix is not invoked during :doc:`energy minim
Restrictions
""""""""""""
This fix is part of the MISC package. It is only enabled if LAMMPS
This fix is part of the EXTRA-FIX package. It is only enabled if LAMMPS
was built with that package. See the :doc:`Build package <Build_package>` page for more info.
Related commands

81
doc/src/fix_polarize.rst
View File

@ -21,7 +21,7 @@ Syntax
* ID, group-ID are documented in :doc:`fix <fix>` command
* style = *polarize/bem/gmres* or *polarize/bem/icc* or *polarize/functional*
* Nevery = this fixed is invoked every this many timesteps
* tolerance = the tolerance for the iterative solver to stop
* tolerance = the relative tolerance for the iterative solver to stop
Examples
@ -45,10 +45,45 @@ Description
"""""""""""
These fixes compute induced charges at the interface between two
impermeable media with different dielectric constants.
impermeable media with different dielectric constants. The interfaces
need to be discretized into vertices, each representing a boundary element.
The vertices are treated as if they were regular atoms or particles.
:doc:`atom_style dielectric <atom_style>` should be used since it defines
the additional properties of each interface particle such as
interface normal vectors, element areas, and local dielectric mismatch.
These fixes also require the use of :doc:`pair_style <pair_style>` and
:doc:`kspace_style <kspace_style>` with the *dielectric* suffix.
At every time step, given a configuration of the physical charges in the system
(such as atoms and charged particles) these fixes compute and update
the charge of the interface particles. The interfaces are allowed to move
during the simulation with appropriate time integrators (for example,
with :doc:`fix_rigid <fix_rigid>`).
There are some example scripts for using this fix
with LAMMPS in the examples/PACKAGES/dielectric directory.
Consider an interface between two media: one with dielectric constant
of 78 (water), the other of 4 (silica). The interface is discretized
into 2000 boundary elements, each represented by an interface particle. Suppose that
each interface particle has a normal unit vector pointing from the silica medium to water.
The dielectric difference along the normal vector is then 78 - 4 = 74,
the mean dielectric value is (78 + 4) / 2 = 41. Each boundary element
also has its area and the local mean curvature (which is used by these fixes
for computing a correction term in the local electric field).
To model charged interfaces, the interface particle will have a non-zero charge value,
coming from its area and surface charge density.
For non-interface particles such as atoms and charged particles,
the interface normal vectors, element area, and dielectric mismatch are
irrelevant. Their local dielectric value is used to rescale their actual charge
when computing the Coulombic interactions. For instance, for a cation carrying
a charge of +2 (in charge unit) in an implicit solvent with dielectric constant of 40
would have actual charge of +2, and a local dielectric constant value of 40.
It is assumed that the particles cannot pass through the interface during the simulation
so that its local dielectric constant value does not change.
There are some example scripts for using these fixes
with LAMMPS in the ``examples/PACKAGES/dielectric directory``. The README file
therein contains specific details on the system setup. Note that the example data files
show the additional fields (columns) needed for :doc:`atom_style dielectric <atom_style>`
beyond the conventional fields *id*, *mol*, *type*, *q*, *x*, *y*, and *z*.
----------
@ -75,12 +110,41 @@ as described in :ref:`(Barros) <Barros>` to solve :math:`\sigma_b`.
Fix *polarize/bem/icc* employs the successive over-relaxation algorithm
as described in :ref:`(Tyagi) <Tyagi>` to solve :math:`\sigma_b`.
Fix *polarize/functional* ...
The iterative solvers would terminate either when the maximum relative change
in the induced charges in consecutive iterations is below the set tolerance,
or when the number of iterations reaches *iter_max* (see below).
Fix *polarize/functional* employs the energy functional variation approach
as described in :ref:`(Jadhao) <Jadhao>` to solve :math:`\sigma_b`.
More details on the implementation of these fixes and their recommended use
are described in :ref:`(NguyenTD) <NguyenTD>`.
Restart, fix_modify, output, run start/stop, minimize info
""""""""""""""""""""""""""""""""""""""""""""""""""""""""""
...
No information about this fix is written to :doc:`binary restart files <restart>`.
The :doc:`fix_modify <fix_modify>` command provides certain options to
control the induced charge solver and the initial values of the interface elements:
.. parsed-literal::
*itr_max* arg
arg = maximum number of iterations for convergence
*dielectrics* ediff emean epsilon area charge
ediff = dielectric difference
emean = dielectric mean
epsilon = local dielectric value
aree = element area
charge = real interface charge
*polarize/bem/gmres* or *polarize/bem/icc* compute a global 2-element vector
which can be accessed by various :doc:`output commands <Howto_output>`.
The first element is the number of iterations when the solver terminates
(of which the upper bound is set by *iter_max*). The second element is the RMS error.
Restrictions
""""""""""""
@ -94,12 +158,15 @@ KSPACE package is installed. See the :doc:`Build package
Related commands
""""""""""""""""
:doc:`pair_coeff <pair_coeff>`, :doc:`fix polarize <fix_polarize>`, :doc:`read_data <read_data>`,
:doc:`pair_style lj/cut/coul/long/dielectric <pair_dielectric>`,
:doc:`kspace_style pppm/dielectric <kspace_style>`,
:doc:`compute efield/atom <compute_efield_atom>`
Default
"""""""
None.
*iter_max* = 20
----------

8
doc/src/fix_qeq.rst
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@ -201,9 +201,11 @@ larger sizes, and *qeq/fire* is faster than *qeq/dynamic*\ .
.. note::
To avoid the evaluation of the derivative of charge with respect
to position, which is typically ill-defined, the system should have a
zero net charge.
In order to solve the self-consistent equations for electronegativity
equalization, LAMMPS imposes the additional constraint that all the
charges in the fix group must add up to zero. The initial charge
assignments should also satisfy this constraint. LAMMPS will print a
warning if that is not the case.
.. note::

8
doc/src/fix_qeq_comb.rst
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@ -63,6 +63,14 @@ performing charge equilibration (more iterations) and accuracy.
If the *file* keyword is used, then information about each
equilibration calculation is written to the specified file.
.. note::
In order to solve the self-consistent equations for electronegativity
equalization, LAMMPS imposes the additional constraint that all the
charges in the fix group must add up to zero. The initial charge
assignments should also satisfy this constraint. LAMMPS will print a
warning if that is not the case.
----------
.. include:: accel_styles.rst

10
doc/src/fix_qeq_reaxff.rst
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@ -77,6 +77,8 @@ of this fix are hard-coded to be A, eV, and electronic charge.
The optional *dual* keyword allows to perform the optimization
of the S and T matrices in parallel. This is only supported for
the *qeq/reaxff/omp* style. Otherwise they are processed separately.
The *qeq/reaxff/kk* style always solves the S and T matrices in
parallel.
The optional *maxiter* keyword allows changing the max number
of iterations in the linear solver. The default value is 200.
@ -88,6 +90,14 @@ same fixed number of QEq iterations is desired, which can be achieved
by using a very small tolerance and setting *maxiter* to the desired
number of iterations.
.. note::
In order to solve the self-consistent equations for electronegativity
equalization, LAMMPS imposes the additional constraint that all the
charges in the fix group must add up to zero. The initial charge
assignments should also satisfy this constraint. LAMMPS will print a
warning if that is not the case.
Restart, fix_modify, output, run start/stop, minimize info
"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""

2
doc/src/fix_smd.rst
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@ -144,7 +144,7 @@ the :doc:`run <run>` command. This fix is not invoked during
Restrictions
""""""""""""
This fix is part of the MISC package. It is only enabled if
This fix is part of the EXTRA-FIX package. It is only enabled if
LAMMPS was built with that package. See the :doc:`Build package <Build_package>` page for more info.
Related commands

9
doc/src/fix_viscosity.rst
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@ -108,10 +108,11 @@ fluid, in appropriate units. See the :ref:`Muller-Plathe paper <Muller-Plathe2>
An alternative method for calculating a viscosity is to run a NEMD
simulation, as described on the :doc:`Howto nemd <Howto_nemd>` doc page.
NEMD simulations deform the simulation box via the :doc:`fix deform <fix_deform>` command. Thus they cannot be run on a charged
system using a :doc:`PPPM solver <kspace_style>` since PPPM does not
currently support non-orthogonal boxes. Using fix viscosity keeps the
box orthogonal; thus it does not suffer from this limitation.
NEMD simulations deform the simulation box via the :doc:`fix deform <fix_deform>` command.
Some features or combination of settings in LAMMPS do not support
non-orthogonal boxes. Using fix viscosity keeps the box orthogonal;
thus it does not suffer from these limitations.
Restart, fix_modify, output, run start/stop, minimize info
"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""

2
doc/src/package.rst
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@ -460,7 +460,7 @@ using *neigh/thread* *on*, a full neighbor list must also be used. Using
is turned on by default only when there are 16K atoms or less owned by
an MPI rank and when using a full neighbor list. Not all KOKKOS-enabled
potentials support this keyword yet, and only thread over atoms. Many
simple pair-wise potentials such as Lennard-Jones do support threading
simple pairwise potentials such as Lennard-Jones do support threading
over both atoms and neighbors.
The *newton* keyword sets the Newton flags for pairwise and bonded

2
doc/src/pair_charmm.rst
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@ -119,7 +119,7 @@ name are the older, original LAMMPS implementations. They compute the
LJ and Coulombic interactions with an energy switching function (esw,
shown in the formula below as S(r)), which ramps the energy smoothly
to zero between the inner and outer cutoff. This can cause
irregularities in pair-wise forces (due to the discontinuous second
irregularities in pairwise forces (due to the discontinuous second
derivative of energy at the boundaries of the switching region), which
in some cases can result in detectable artifacts in an MD simulation.

2
doc/src/pair_dpd.rst
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@ -50,7 +50,7 @@ Style *dpd* computes a force field for dissipative particle dynamics
Style *dpd/tstat* invokes a DPD thermostat on pairwise interactions,
which is equivalent to the non-conservative portion of the DPD force
field. This pair-wise thermostat can be used in conjunction with any
field. This pairwise thermostat can be used in conjunction with any
:doc:`pair style <pair_style>`, and in leiu of per-particle thermostats
like :doc:`fix langevin <fix_langevin>` or ensemble thermostats like
Nose Hoover as implemented by :doc:`fix nvt <fix_nh>`. To use

90
doc/src/pair_harmonic_cut.rst Normal file
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@ -0,0 +1,90 @@
.. index:: pair_style harmonic/cut
.. index:: pair_style harmonic/cut/omp
pair_style harmonic/cut command
===============================
Accelerator Variants: *harmonic/cut/omp*
Syntax
""""""
.. code-block:: LAMMPS
pair_style style
* style = *harmonic/cut*
Examples
""""""""
.. code-block:: LAMMPS
pair_style harmonic/cut
pair_coeff * * 0.2 2.0
pair_coeff 1 1 0.5 2.5
Description
"""""""""""
Style *harmonic/cut* computes pairwise repulsive-only harmonic interactions with the formula
.. math::
E = k (r_c - r)^2 \qquad r < r_c
:math:`r_c` is the cutoff.
The following coefficients must be defined for each pair of atoms
types via the :doc:`pair_coeff <pair_coeff>` command as in the examples
above, or in the data file or restart files read by the
:doc:`read_data <read_data>` or :doc:`read_restart <read_restart>`
commands:
* :math:`k` (energy units)
* :math:`r_c` (distance units)
----------
.. include:: accel_styles.rst
----------
Mixing, shift, table, tail correction, restart, rRESPA info
"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""
For atom type pairs I,J and I != J, the :math:`k` and :math:`r_c`
coefficients can be mixed. The default mix value is *geometric*.
See the "pair_modify" command for details.
Since the potential is zero at and beyond the cutoff parameter by
construction, there is no need to support the :doc:`pair_modify
<pair_modify>` shift or tail options for the energy and pressure of the
pair interaction.
These pair styles write their information to :doc:`binary restart files <restart>`,
so pair_style and pair_coeff commands do not need to be specified in an input script
that reads a restart file.
These pair styles can only be used via the *pair* keyword of the
:doc:`run_style respa <run_style>` command. They do not support the
*inner*, *middle*, *outer* keywords.
----------
Restrictions
""""""""""""
The *harmonic/cut* pair style is only enabled if LAMMPS was
built with the EXTRA-PAIR package.
See the :doc:`Build package <Build_package>` page for more info.
Related commands
""""""""""""""""
:doc:`pair_coeff <pair_coeff>`
Default
"""""""
none

2
doc/src/pair_ilp_graphene_hbn.rst
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@ -159,6 +159,8 @@ Related commands
:doc:`pair_none <pair_none>`,
:doc:`pair_style hybrid/overlay <pair_hybrid>`,
:doc:`pair_style drip <pair_drip>`,
:doc:`pair_style ilp_tmd <pair_ilp_tmd>`,
:doc:`pair_style saip_metal <pair_saip_metal>`,
:doc:`pair_style pair_kolmogorov_crespi_z <pair_kolmogorov_crespi_z>`,
:doc:`pair_style pair_kolmogorov_crespi_full <pair_kolmogorov_crespi_full>`,
:doc:`pair_style pair_lebedeva_z <pair_lebedeva_z>`,

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