hover to animate -- input script physical analog (start at 3:25) & explanation

LAMMPS is a classical molecular dynamics code, and an acronym for Large-scale Atomic/Molecular Massively Parallel Simulator.

LAMMPS has potentials for solid-state materials (metals, semiconductors) and soft matter (biomolecules, polymers) and coarse-grained or mesoscopic systems. It can be used to model atoms or, more generically, as a parallel particle simulator at the atomic, meso, or continuum scale.

LAMMPS runs on single processors or in parallel using message-passing techniques and a spatial-decomposition of the simulation domain. The code is designed to be easy to modify or extend with new functionality.

LAMMPS is distributed as an open source code under the terms of the GPL. The current version can be downloaded here. Links are also included to older F90/F77 versions. Periodic releases are also available on SourceForge.

LAMMPS is distributed by Sandia National Laboratories, a US Department of Energy laboratory. The main authors of LAMMPS are listed on this page along with contact info and other contributors. Funding for LAMMPS development has come primarily from DOE (OASCR, OBER, ASCI, LDRD, Genomes-to-Life) and is acknowledged here.

The LAMMPS WWW site is hosted by Sandia, which has this Privacy and Security statement.

• (2/14) Added "stable" versions of LAMMPS to the download page, which undergo more testing than the incremental versions. Hopefully this makes it easier for users to upgrade their version only periodically.
• (1/14) Added an idea due to John Grime (U Chicago), to define templates of molecular topology info for systems with many small molecules, to avoid the memory cost of duplicating the information. See the atom_style template command for details.
• (1/14) Added MPI-IO support for reading/writing restart and dump files in parallel.
• (1/14) Added support for 64-bit atom IDs, so that molecular systems with up to 2^63 = ~9e19 atoms can be modeled. See Section 2.4 of the manual for how to enable this option at build time.
• (12/13) Significant features added to LAMMPS in the fourth quarter of 2013 include a new write_dump command, dump movie, pair comb3, fix ti/rs and fix ti/spring, compute vacf, new USER-LB package for Lattice-Boltzmann background fluid, enhancements to neb command, write_data command to replace restart2data tool, parallel write/read of restart files, new molecule command, fix deposit molecule, fix pour molecule See authors here and details here.
• (12/13) Added a molecule command to allow molecule templates to be defined, e.g. for insertion of flexible or rigid molecules via the fix deposit and fix pour commands.
• (11/13) Release of USER-LB package which implements a background Lattice Boltzmann fluid with hydrodynamic forces on particles; see the fix lb/fluid command.
• (11/13) Release of 3rd-generation COMB (COMB3) potential as pair_style comb3 command.
• (11/13) Released a dump movie command so that movie files (in various formats) can be made directly from a LAMMPS run.
• (9/13) Significant features added to LAMMPS in the third quarter of 2013 include pair nb3b/harmonic, allow poly-disperse granular systems to have widely varying neighbors/particle, atomfile-style variables, fix property/atom to add new user-defined attributes to atoms, fix gld, compute basal/atom, pair tersoff/mod, pair peri/ves, new version of USER-ATC package and GPU package, fix wall/lj1043, pair nm/cut, pair nm/cut/coul/cut, pair nm/cut/coul/long, compute ke/rigid, compute erotate/rigid, example dirs ASPHERE, KAPPA, VISCOSITY, pair zbl, xmgrace tool. See authors here and details here.
• (9/13) Released examples/ASPHERE and examples/KAPPA and examples/VISCOSITY directories. The first has demonstration scripts for modeling aspherical particles of the various kinds that LAMMPS allows, including point ellipsoids, rigid bodies, and line/triangle surface facets for 2d/3d. Animations of the script outputs have been added to the Movies page. The latter two have demonstration scripts for computing thermal conductivities and viscosities, each with 4 different methods.
• (8/13) The 3rd LAMMPS workshop was held in Albuquerque. See the program and PDFs of most of the presentations at the Workshops link.
• (6/13) Significant features added to LAMMPS in the second quarter of 2013 include dump modify nfile and fileper for improved parallel I/O performance, write_data, triclinic support for PPPM/MSM/Ewald long-range solvers, delete_atoms mol, pair list, pair lj/cut/dipole/long and lj/long/coul/long, long-range dipole support in kspace_style ewald/disp, fix langevin gjf, fix tune/kspace, significant upgrade to the USER-COLVARS package, kspace_style pppm/stagger. See authors here and details here.
• (5/13) Added triclinic support for PPPM and MSM and Ewald long-range solvers.
• (3/13) Significant features added to LAMMPS in the first quarter of 2013 include kspace_style msm for non-periodic boundaries, more commands now allow for equal- and atom-style variable inputs, compute voronoi/atom, atom_style body and the BODY package, fix rigid/small, fix species, syntax for immediate variable evaluation in input scripts, pair lj/cut/tip4p/cut, and fix phonon and the USER-PHONON package. See authors here and details here.
• (3/13) New fix phonon command for calculating dynamical matrices and phonon dispersion relations.
• (2/13) New fix rigid/small command for modeling large numbers of small rigid bodies more scalably in parallel.
• (2/13) New body package for working with generalized aspherical particles.
• (1/13) Pre-built LAMMPS executable available as a Ubuntu Linux package and Mac OS X package.
• Old

This is work by Shengfeng Cheng (chengsf at vt.edu) at Virginia Tech and Gary Grest at Sandia, to model self-assembly of nanoparticles at a liquid-vapor interface, induced by evaporation of the surrounding solvent. The quality of the remaining nanoparticle crystal structure is a result of the competition between evaporation rate and nanoparticle diffusion time.

The first figure shows snapshots of the simulation from different views. The second is a Voronoi tesselation of the top layer of the nanoparticle substrate. The coloring in both figures is based on a hexagonal order parameter for the local neighborhood of each particle. The third figure is an animation of the evaporation and ordering process.

This paper has further details:

Molecular dynamics simulations of evaporation-induced nanoparticle assembly, S. Cheng and G. S. Grest, J Chem Phys, 138, 064701 (2013). (abstract)