This is the home page for the classical molecular dynamics code LAMMPS, an acronym for Large-scale Atomic/Molecular Massively Parallel Simulator. The current version of LAMMPS is 21 May 2008.

LAMMPS has potentials for soft materials (biomolecules, polymers) and solid-state materials (metals, semiconductors) 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. This includes links to the last major release, the latest upgraded version with all subsequent bug fixes and new features, and older F90/F77 versions. The last major release is also available on SourceForge.

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

• (7/08) Addition of particle-based Peridynamics continuum model with new atom_style and force field.
• (5/08) Posted some benchmark numbers for LAMMPS running on a Dell desktop box with dual quad-core Intel Xeon chips.
• (5/08) Release of 21 May 2008 version of LAMMPS. New features include a revamping of how temperatures are computed with bias velocities subtracted and how they work with various thermostats, and a more robust line-search and stopping criteria in energy minimization. New commands added are angle_style cosine/delta, compute group/group, compute reduce, fix temp/berendsen, fix press/berendsen, fix nve/sphere, fix nvt/sphere, fix npt/sphere, compute temp/com, compute temp/sphere, compute erotate/sphere, compute erotate/asphere, fix thermal/conductivity, pair_style lj/gromacs, pair_style lj/gromacs/coul/gromacs, and fix bond/swap. The delete_atoms overlap command was enhanced. Two new tools were added: a lmp2vmd tool for post-processing to VMD format and a directory of Python post-processing scripts. Two USER packages were also added: a USER-CG-CMM package for coarse-grained models and a USER-SMD package for steered MD. See details here.
• (1/08) Release of 22 Jan 2008 version of LAMMPS. New features include revamped LAMMPS output options for thermodynamic and dump output, thermo_style custom and dump custom can now access computes, fixes, and variables directly, new enhanced versions of the fix ave/time, fix ave/spatial, and fix ave/atom commands, per-atom energy and virial tabulations for all pair and many-body potentials and fixes that invoke internal constraints, and a new easier-to-use variable formula syntax. New commands added are fix dt/reset, pair_style lubricate, pair coul/debye, fix coord/original, compute pe/atom, compute stress/atom, compute sum, pair_style resquared, fix viscosity, and compute displace/atom. Deprecated commands are "fix gran/diag", "compute epair/atom", "compute ebond/atom", "compute variable/atom", "compute variable", "compute sum/atom", and "compute attribute/atom". See details here.
• (10/07) Release of 5 Oct 2007 version of LAMMPS. New features include displace_box, change_box, compute ebond/atom, changes to 2d pressure computation, rigid bodies with fix deform, pair_style airebo, fix nve/limit, fix ave/atom, compute attribute/atom, compute sum/atom, user-contributed packages, pair_style hybrid/overlay for superposing pairwise potentials, kspace_style ewald/n for long-range dispersion contributions from 1/r^6 LJ terms, pair_style lj/coul, pair_style buck/coul, compute ackland/atom. See details here.
• (6/07) Release of 22 Jun 2007 version of LAMMPS. New features include static and dynamic non-orthogonal simulation boxes (triclinic symmetry), fix heat, if command, new Finnis/Sinclair EAM potentials, displace_atoms random, new set options, create_atoms single, compute coord/atom, fix ave/time, fix ave/spatial, variable atom, new COLLOID package with pair colloid potential and neighbor and communication options to support it, new DIPOLE package for point-dipole particles with pair dipole/cut, new ASPHERE package for ellipsoidal particles with a GayBerne potential and aspherical particle integrators to support it, NEMD simulations via fix deform and fix nvt/sllod and compute temp/deform, and tools/pymol_asphere for ellipsoidal particles. See details here.
• Old

This is work by Seung Soon Jang (jsshys at wag.caltech.edu) in Bill Goddard's group at Cal Tech.

The 1st picture/paper are for a model they've developed of a dendrion diblock copolymer consisting of a dendritic polymer with a hydrophobic backbone. Such materials have interesting nanoscale structural and phase behavior.

The 2nd picture/paper are for simulations of amphiphilic bistable (2)rotaxane molecules which have controllable switching properties as their conformation changes.

The 3rd picture/paper are studies of the structure and surface concentrations of different surfactants in thin Newton black films.

The 1st picture shows the molecular structures of a diblock copolymer system at two different levels of water content. The 2nd picture illustrates conformational changes in a Langmuir monolayer of the rotaxane molecules. The 3rd picture shows film structure at varying surface concentrations (top) and film thicknesses (bottom).

These papers have further details:

Nanophase-segregation and water dynamics in the dendrion diblock copolymer formed from polyaryl ethereal dendrimer and linear PTFE, S. S. Jang, S.-T. Lin, T. Cagin, V. Molinero and W. A. Goddard III, J Phys Chem B, 109, 10154-10167 (2005). (abstract)

Molecular dynamics simulation of amphiphilic bistable (2)rotaxane Langmuir monolayer at air/water interface, S. S. Jang, Y. H. Jang, Y.-H. Kim, W. A. Goddard III, J. W. Choi, J. R. Heath, A. H. Flood, B. W. Laursen, and J. F. Stoddart, J Amer Chem Soc, 127, 14804 (2005). (abstract)

Structures and Properties of Newton Black Films Characterized Using Molecular Dynamics Simulations, S. S. Jang and W. A. Goddard III, J Phys Chem B, 110, 7992-8001 (2006). (abstract)