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Merge branch 'develop' into Elastic_stress

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Axel Kohlmeyer
2022-04-23 04:35:23 -04:00
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3
doc/src/Developer_utils.rst
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@ -211,6 +211,9 @@ Convenience functions
.. doxygenfunction:: logmesg(LAMMPS *lmp, const std::string &mesg)
:project: progguide
.. doxygenfunction:: errorurl
:project: progguide
.. doxygenfunction:: flush_buffers(LAMMPS *lmp)
:project: progguide

1
doc/src/Errors.rst
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@ -11,6 +11,7 @@ them.
:maxdepth: 1
Errors_common
Errors_details
Errors_bugs
Errors_debug
Errors_messages

27
doc/src/Errors_details.rst Normal file
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@ -0,0 +1,27 @@
Detailed discussion of errors and warnings
==========================================
Many errors or warnings are self-explanatory and thus straightforward to
resolve. However, there are also cases, where there is no single cause
and explanation, where LAMMPS can only detect symptoms of an error but
not the exact cause, or where the explanation needs to be more detailed than
what can be fit into a message printed by the program. The following are
discussions of such cases.
.. _err0001:
Unknown identifier in data file
-------------------------------
This error happens when LAMMPS encounters a line of text in an unexpected format
while reading a data file. This is most commonly cause by inconsistent header and
section data. The header section informs LAMMPS how many entries or lines are expected in the
various sections (like Atoms, Masses, Pair Coeffs, *etc.*\ ) of the data file.
If there is a mismatch, LAMMPS will either keep reading beyond the end of a section
or stop reading before the section has ended.
Such a mismatch can happen unexpectedly when the first line of the data
is *not* a comment as required by the format. That would result in
LAMMPS expecting, for instance, 0 atoms because the "atoms" header line
is treated as a comment.

81
doc/src/Modify_atom.rst
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@ -9,34 +9,34 @@ A new atom style can be created if one of the existing atom styles
does not define all the attributes you need to store and communicate
with atoms.
Atom_vec_atomic.cpp is the simplest example of an atom style.
The file ``atom_vec_atomic.cpp`` is the simplest example of an atom style.
Examining the code for others will make these instructions more clear.
Note that the :doc:`atom style hybrid <atom_style>` command can be
used to define atoms or particles which have the union of properties
of individual styles. Also the :doc:`fix property/atom <fix_property_atom>`
command can be used to add a single property (e.g. charge
or a molecule ID) to a style that does not have it. It can also be
used to add custom properties to an atom, with options to communicate
them with ghost atoms or read them from a data file. Other LAMMPS
commands can access these custom properties, as can new pair, fix,
compute styles that are written to work with these properties. For
Note that the :doc:`atom style hybrid <atom_style>` command can be used
to define atoms or particles which have the union of properties of
individual styles. Also the :doc:`fix property/atom
<fix_property_atom>` command can be used to add a single property
(e.g. charge or a molecule ID) to a style that does not have it. It can
also be used to add custom properties to an atom, with options to
communicate them with ghost atoms or read them from a data file. Other
LAMMPS commands can access these custom properties, as can new pair,
fix, compute styles that are written to work with these properties. For
example, the :doc:`set <set>` command can be used to set the values of
custom per-atom properties from an input script. All of these methods
are less work than writing code for a new atom style.
are less work than writing and testing(!) code for a new atom style.
If you follow these directions your new style will automatically work
in tandem with others via the :doc:`atom_style hybrid <atom_style>`
command.
The first step is to define a set of strings in the constructor of the
new derived class. Each string will have zero or more space-separated
variable names which are identical to those used in the atom.h header
file for per-atom properties. Note that some represent per-atom
The first step is to define a set of string lists in the constructor of
the new derived class. Each list will have zero or more comma-separated
strings that correspond to the variable names used in the ``atom.h``
header file for per-atom properties. Note that some represent per-atom
vectors (q, molecule) while other are per-atom arrays (x,v). For all
but the last 2 strings you do not need to specify any of
but the last two lists you do not need to specify any of
(id,type,x,v,f). Those are included automatically as needed in the
other strings.
other lists.
.. list-table::
@ -65,16 +65,16 @@ other strings.
* - fields_data_vel
- list of properties (in order) in the Velocities section of a data file, as read by :doc:`read_data <read_data>`
In these strings you can list variable names which LAMMPS already
defines (in some other atom style), or you can create new variable
names. You should not re-use a LAMMPS variable for something with
different meaning in your atom style. If the meaning is related, but
interpreted differently by your atom style, then using the same
variable name means a user should not use your style and the other
style together in a :doc:`atom_style hybrid <atom_style>` command.
Because there will only be one value of the variable and different
parts of LAMMPS will then likely use it differently. LAMMPS has
no way of checking for this.
In these lists you can list variable names which LAMMPS already defines
(in some other atom style), or you can create new variable names. You
should not re-use a LAMMPS variable in your atom style that is used for
something with a different meaning in another atom style. If the
meaning is related, but interpreted differently by your atom style, then
using the same variable name means a user must not use your style and
the other style together in a :doc:`atom_style hybrid <atom_style>`
command. Because there will only be one value of the variable and
different parts of LAMMPS will then likely use it differently. LAMMPS
has no way of checking for this.
If you are defining new variable names then make them descriptive and
unique to your new atom style. For example choosing "e" for energy is
@ -85,32 +85,31 @@ If any of the variable names in your new atom style do not exist in
LAMMPS, you need to add them to the src/atom.h and atom.cpp files.
Search for the word "customize" or "customization" in these 2 files to
see where to add your variable. Adding a flag to the 2nd
customization section in atom.h is only necessary if your code (e.g. a
pair style) needs to check that a per-atom property is defined. These
flags should also be set in the constructor of the atom style child
class.
see where to add your variable. Adding a flag to the 2nd customization
section in ``atom.h`` is only necessary if your code (e.g. a pair style)
needs to check that a per-atom property is defined. These flags should
also be set in the constructor of the atom style child class.
In atom.cpp, aside from the constructor and destructor, there are 3
In ``atom.cpp``, aside from the constructor and destructor, there are 3
methods that a new variable name or flag needs to be added to.
In Atom::peratom_create() when using the add_peratom() method, a
final length argument of 0 is for per-atom vectors, a length > 1 is
for per-atom arrays. Note the use of an extra per-thread flag and the
add_peratom_vary() method when last dimension of the array is
In ``Atom::peratom_create()`` when using the ``Atom::add_peratom()``
method, a cols argument of 0 is for per-atom vectors, a length >
1 is for per-atom arrays. Note the use of the extra per-thread flag and
the add_peratom_vary() method when last dimension of the array is
variable-length.
Adding the variable name to Atom::extract() enable the per-atom data
Adding the variable name to Atom::extract() enables the per-atom data
to be accessed through the :doc:`LAMMPS library interface
<Howto_library>` by a calling code, including from :doc:`Python
<Python_head>`.
The constructor of the new atom style will also typically set a few
flags which are defined at the top of atom_vec.h. If these are
flags which are defined at the top of ``atom_vec.h``. If these are
unclear, see how other atom styles use them.
The grow_pointers() method is also required to make
a copy of peratom data pointers, as explained in the code.
The grow_pointers() method is also required to make a copy of peratom
data pointers, as explained in the code.
There are a number of other optional methods which your atom style can
implement. These are only needed if you need to do something

7
doc/src/compute_rigid_local.rst
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@ -127,19 +127,16 @@ The *vx*, *vy*, *vz*, *fx*, *fy*, *fz* attributes are components of
the COM velocity and force on the COM of the body.
The *omegax*, *omegay*, and *omegaz* attributes are the angular
velocity components of the body around its COM.
velocity components of the body in the system frame around its COM.
The *angmomx*, *angmomy*, and *angmomz* attributes are the angular
momentum components of the body around its COM.
momentum components of the body in the system frame around its COM.
The *quatw*, *quati*, *quatj*, and *quatk* attributes are the
components of the 4-vector quaternion representing the orientation of
the rigid body. See the :doc:`set <set>` command for an explanation of
the quaternion vector.
The *angmomx*, *angmomy*, and *angmomz* attributes are the angular
momentum components of the body around its COM.
The *tqx*, *tqy*, *tqz* attributes are components of the torque acting
on the body around its COM.

45
doc/src/compute_temp_profile.rst
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@ -76,21 +76,28 @@ velocity for each atom. Note that if there is only one atom in the
bin, its thermal velocity will thus be 0.0.
After the spatially-averaged velocity field has been subtracted from
each atom, the temperature is calculated by the formula KE = (dim\*N
- dim\*Nx\*Ny\*Nz) k T/2, where KE = total kinetic energy of the group of
atoms (sum of 1/2 m v\^2), dim = 2 or 3 = dimensionality of the
simulation, N = number of atoms in the group, k = Boltzmann constant,
and T = temperature. The dim\*Nx\*Ny\*Nz term are degrees of freedom
subtracted to adjust for the removal of the center-of-mass velocity in
each of Nx\*Ny\*Nz bins, as discussed in the :ref:`(Evans) <Evans1>` paper.
each atom, the temperature is calculated by the formula
*KE* = (*dim\*N* - *Ns\*Nx\*Ny\*Nz* - *extra* ) *k* *T*/2, where *KE* = total
kinetic energy of the group of atoms (sum of 1/2 *m* *v*\^2), *dim* = 2
or 3 = dimensionality of the simulation, *Ns* = 0, 1, 2 or 3 for
streaming velocity subtracted in 0, 1, 2 or 3 dimensions, *extra* = extra
degrees-of-freedom, *N* = number of atoms in the group, *k* = Boltzmann
constant, and *T* = temperature. The *Ns\*Nx\*Ny\*Nz* term is degrees
of freedom subtracted to adjust for the removal of the center-of-mass
velocity in each direction of the *Nx\*Ny\*Nz* bins, as discussed in the
:ref:`(Evans) <Evans1>` paper. The extra term defaults to (*dim* - *Ns*)
and accounts for overall conservation of center-of-mass velocity across
the group in directions where streaming velocity is *not* subtracted. This
can be altered using the *extra* option of the
:doc:`compute_modify <compute_modify>` command.
If the *out* keyword is used with a *tensor* value, which is the
default, a kinetic energy tensor, stored as a 6-element vector, is
also calculated by this compute for use in the computation of a
pressure tensor. The formula for the components of the tensor is the
same as the above formula, except that v\^2 is replaced by vx\*vy for
the xy component, etc. The 6 components of the vector are ordered xx,
yy, zz, xy, xz, yz.
same as the above formula, except that *v*\^2 is replaced by *vx\*vy* for
the xy component, etc. The 6 components of the vector are ordered *xx,
yy, zz, xy, xz, yz.*
If the *out* keyword is used with a *bin* value, the count of atoms
and computed temperature for each bin are stored for output, as an
@ -123,10 +130,20 @@ needed, the subtracted degrees-of-freedom can be altered using the
.. note::
When using the *out* keyword with a value of *bin*, the
calculated temperature for each bin does not include the
degrees-of-freedom adjustment described in the preceding paragraph,
for fixes that constrain molecular motion. It does include the
adjustment due to the *extra* option, which is applied to each bin.
calculated temperature for each bin includes the degrees-of-freedom
adjustment described in the preceding paragraph for fixes that
constrain molecular motion, as well as the adjustment due to
the *extra* option (which defaults to *dim* - *Ns* as described above),
by fractionally applying them based on the fraction of atoms in each
bin. As a result, the bin degrees-of-freedom summed over all bins exactly
equals the degrees-of-freedom used in the scalar temperature calculation,
:math:`\Sigma N_{DOF_i} = N_{DOF}` and the corresponding relation for temperature
is also satisfied :math:`\Sigma N_{DOF_i} T_i = N_{DOF} T`.
These relations will breakdown in cases where the adjustment
exceeds the actual number of degrees-of-freedom in a bin. This could happen
if a bin is empty or in situations where rigid molecules
are non-uniformly distributed, in which case the reported
temperature within a bin may not be accurate.
See the :doc:`Howto thermostat <Howto_thermostat>` page for a
discussion of different ways to compute temperature and perform

87
doc/src/fix_adapt.rst
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@ -14,7 +14,7 @@ Syntax
* adapt = style name of this fix command
* N = adapt simulation settings every this many timesteps
* one or more attribute/arg pairs may be appended
* attribute = *pair* or *bond* or *kspace* or *atom*
* attribute = *pair* or *bond* or *angle* or *kspace* or *atom*
.. parsed-literal::
@ -28,11 +28,16 @@ Syntax
bparam = parameter to adapt over time
I = type bond to set parameter for
v_name = variable with name that calculates value of bparam
*angle* args = astyle aparam I v_name
astyle = angle style name, e.g. harmonic
aparam = parameter to adapt over time
I = type angle to set parameter for
v_name = variable with name that calculates value of aparam
*kspace* arg = v_name
v_name = variable with name that calculates scale factor on K-space terms
*atom* args = aparam v_name
aparam = parameter to adapt over time
v_name = variable with name that calculates value of aparam
*atom* args = atomparam v_name
atomparam = parameter to adapt over time
v_name = variable with name that calculates value of atomparam
* zero or more keyword/value pairs may be appended
* keyword = *scale* or *reset* or *mass*
@ -283,30 +288,62 @@ operates. The only difference is that now a bond coefficient for a
given bond type is adapted.
A wild-card asterisk can be used in place of or in conjunction with
the bond type argument to set the coefficients for multiple bond types.
This takes the form "\*" or "\*n" or "n\*" or "m\*n". If N = the number of
atom types, then an asterisk with no numeric values means all types
from 1 to N. A leading asterisk means all types from 1 to n (inclusive).
A trailing asterisk means all types from n to N (inclusive). A middle
asterisk means all types from m to n (inclusive).
the bond type argument to set the coefficients for multiple bond
types. This takes the form "\*" or "\*n" or "n\*" or "m\*n". If N =
the number of bond types, then an asterisk with no numeric values
means all types from 1 to N. A leading asterisk means all types from
1 to n (inclusive). A trailing asterisk means all types from n to N
(inclusive). A middle asterisk means all types from m to n
(inclusive).
Currently *bond* does not support bond_style hybrid nor bond_style
hybrid/overlay as bond styles. The only bonds that currently are
working with fix_adapt are
hybrid/overlay as bond styles. The bond styles that currently work
with fix_adapt are
+------------------------------------+-------+------------+
| :doc:`class2 <bond_class2>` | r0 | type bonds |
+------------------------------------+-------+------------+
| :doc:`fene <bond_fene>` | k, r0 | type bonds |
+------------------------------------+-------+------------+
| :doc:`gromos <bond_gromos>` | k, r0 | type bonds |
+------------------------------------+-------+------------+
| :doc:`harmonic <bond_harmonic>` | k,r0 | type bonds |
+------------------------------------+-------+------------+
| :doc:`morse <bond_morse>` | r0 | type bonds |
+------------------------------------+-------+------------+
| :doc:`nonlinear <bond_nonlinear>` | r0 | type bonds |
+------------------------------------+-------+------------+
+------------------------------------+-------+-----------------+
| :doc:`class2 <bond_class2>` | r0 | type bonds |
+------------------------------------+-------+-----------------+
| :doc:`fene <bond_fene>` | k,r0 | type bonds |
+------------------------------------+-------+-----------------+
| :doc:`fene/nm <bond_fene_nm>` | k,r0 | type bonds |
+------------------------------------+-------+-----------------+
| :doc:`gromos <bond_gromos>` | k,r0 | type bonds |
+------------------------------------+-------+-----------------+
| :doc:`harmonic <bond_harmonic>` | k,r0 | type bonds |
+------------------------------------+-------+-----------------+
| :doc:`morse <bond_morse>` | r0 | type bonds |
+------------------------------------+-------+-----------------+
| :doc:`nonlinear <bond_nonlinear>` | epsilon,r0 | type bonds |
+------------------------------------+-------+-----------------+
----------
The *angle* keyword uses the specified variable to change the value of
an angle coefficient over time, very similar to how the *pair* keyword
operates. The only difference is that now an angle coefficient for a
given angle type is adapted.
A wild-card asterisk can be used in place of or in conjunction with
the angle type argument to set the coefficients for multiple angle
types. This takes the form "\*" or "\*n" or "n\*" or "m\*n". If N =
the number of angle types, then an asterisk with no numeric values
means all types from 1 to N. A leading asterisk means all types from
1 to n (inclusive). A trailing asterisk means all types from n to N
(inclusive). A middle asterisk means all types from m to n
(inclusive).
Currently *angle* does not support angle_style hybrid nor angle_style
hybrid/overlay as angle styles. The angle styles that currently work
with fix_adapt are
+------------------------------------+-------+-----------------+
| :doc:`harmonic <angle_harmonic>` | k,theta0 | type angles |
+------------------------------------+-------+-----------------+
| :doc:`cosine <angle_cosine>` | k | type angles |
+------------------------------------+-------+-----------------+
Note that internally, theta0 is stored in radians, so the variable
this fix uses to reset theta0 needs to generate values in radians.
----------

6
doc/src/fix_nve.rst
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@ -35,6 +35,10 @@ consistent with the microcanonical ensemble (NVE) provided there
are (full) periodic boundary conditions and no other "manipulations"
of the system (e.g. fixes that modify forces or velocities).
This fix invokes the velocity form of the
Störmer-Verlet time integration algorithm (velocity-Verlet). Other
time integration options can be invoked using the :doc:`run_style <run_style>` command.
----------
.. include:: accel_styles.rst
@ -57,7 +61,7 @@ Restrictions
Related commands
""""""""""""""""
:doc:`fix nvt <fix_nh>`, :doc:`fix npt <fix_nh>`
:doc:`fix nvt <fix_nh>`, :doc:`fix npt <fix_nh>`, :doc:`run_style <run_style>`
Default
"""""""

16
doc/src/fix_property_atom.rst
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@ -304,13 +304,15 @@ uninterrupted fashion.
.. warning::
When reading data from a restart file, this fix command has to be
specified **exactly** the same was in the input script that created
the restart file. LAMMPS will only check whether a fix is of the
same style and has the same fix ID and in case of a match will then
try to initialize the fix with the data stored in the binary
restart file. If the names and associated date types in the new
fix property/atom command do not match the old one exactly, data
can be corrupted or LAMMPS may crash.
specified **after** the *read_restart* command and **exactly** the
same was in the input script that created the restart file. LAMMPS
will only check whether a fix is of the same style and has the same
fix ID and in case of a match will then try to initialize the fix
with the data stored in the binary restart file. If the names and
associated date types in the new fix property/atom command do not
match the old one exactly, data can be corrupted or LAMMPS may crash.
If the fix is specified **before** the *read_restart* command its
data will not be restored.
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

2
doc/src/fix_ttm.rst
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@ -217,7 +217,7 @@ units used.
.. note::
The electronic temperature at each grid point must be a non-zero
positive value, both initially, and as the temperature evovles over
positive value, both initially, and as the temperature evolves over
time. Thus you must use either the *set* or *infile* keyword or be
restarting a simulation that used this fix previously.

16
doc/src/group.rst
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@ -258,11 +258,17 @@ assignment is made at the beginning of the minimization, but not
during the iterations of the minimizer.
The point in the timestep at which atoms are assigned to a dynamic
group is after the initial stage of velocity Verlet time integration
has been performed, and before neighbor lists or forces are computed.
This is the point in the timestep where atom positions have just
changed due to the time integration, so the region criterion should be
accurate, if applied.
group is after interatomic forces have been computed, but before any
fixes which alter forces or otherwise update the system have been
invoked. This means that atom positions have been updated, neighbor
lists and ghost atoms are current, and both intermolecular and
intramolecular forces have been calculated based on the new
coordinates. Thus the region criterion, if applied, should be
accurate. Also, any computes invoked by an atom-style variable should
use updated information for that timestep, e.g. potential energy/atom
or coordination number/atom. Similarly, fixes or computes which are
invoked after that point in the timestep, should operate on the new
group of atoms.
.. note::

3
doc/src/run_style.rst
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@ -67,7 +67,8 @@ Description
Choose the style of time integrator used for molecular dynamics
simulations performed by LAMMPS.
The *verlet* style is a standard velocity-Verlet integrator.
The *verlet* style is the velocity form of the
Störmer-Verlet time integration algorithm (velocity-Verlet)
----------

2
doc/src/thermo_modify.rst
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@ -252,6 +252,6 @@ flush = no, and temp/press = compute IDs defined by thermo_style.
The defaults for the line and format options depend on the thermo style.
For styles "one" and "custom", the line and format defaults are "one",
"%10d", and "%12.8g". For style "multi", the line and format defaults
"%10d", and "%14.8g". For style "multi", the line and format defaults
are "multi", "%14d", and "%14.4f". For style "yaml", the line and format
defaults are "%d" and "%.15g".

2
doc/src/thermo_style.rst
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@ -10,7 +10,7 @@ Syntax
thermo_style style args
* style = *one* or *multi* *yaml* or *custom*
* style = *one* or *multi* or *yaml* or *custom*
* args = list of arguments for a particular style
.. parsed-literal::