49 lines
2.2 KiB
ReStructuredText
49 lines
2.2 KiB
ReStructuredText
Overview of LAMMPS
|
|
==================
|
|
|
|
LAMMPS is a classical molecular dynamics (MD) code that models
|
|
ensembles of particles in a liquid, solid, or gaseous state. It can
|
|
model atomic, polymeric, biological, solid-state (metals, ceramics,
|
|
oxides), granular, coarse-grained, or macroscopic systems using a
|
|
variety of interatomic potentials (force fields) and boundary
|
|
conditions. It can model 2d or 3d systems with only a few particles
|
|
up to millions or billions.
|
|
|
|
LAMMPS can be built and run on a laptop or desktop machine, but is
|
|
designed for parallel computers. It will run on any parallel machine
|
|
that supports the `MPI <mpi_>`_ message-passing library. This includes
|
|
shared-memory boxes and distributed-memory clusters and
|
|
supercomputers.
|
|
|
|
.. _mpi: https://en.wikipedia.org/wiki/Message_Passing_Interface
|
|
.. _lws: https://lammps.sandia.gov
|
|
|
|
LAMMPS is written in C++. Earlier versions were written in F77 and
|
|
F90. See the `History page <https://lammps.sandia.gov/history.html>`_ of
|
|
the website for details. All versions can be downloaded from the
|
|
`LAMMPS website <lws_>`_.
|
|
|
|
LAMMPS is designed to be easy to modify or extend with new
|
|
capabilities, such as new force fields, atom types, boundary
|
|
conditions, or diagnostics. See the :doc:`Modify <Modify>` doc page for
|
|
more details.
|
|
|
|
In the most general sense, LAMMPS integrates Newton's equations of
|
|
motion for a collection of interacting particles. A single particle
|
|
can be an atom or molecule or electron, a coarse-grained cluster of
|
|
atoms, or a mesoscopic or macroscopic clump of material. The
|
|
interaction models that LAMMPS includes are mostly short-range in
|
|
nature; some long-range models are included as well.
|
|
|
|
LAMMPS uses neighbor lists to keep track of nearby particles. The
|
|
lists are optimized for systems with particles that are repulsive at
|
|
short distances, so that the local density of particles never becomes
|
|
too large. This is in contrast to methods used for modeling plasma
|
|
or gravitational bodies (e.g. galaxy formation).
|
|
|
|
On parallel machines, LAMMPS uses spatial-decomposition techniques to
|
|
partition the simulation domain into small sub-domains of equal
|
|
computational cost, one of which is assigned to each processor.
|
|
Processors communicate and store "ghost" atom information for atoms
|
|
that border their sub-domain.
|