LAMMPS example problems

Each of these sub-directories contains a sample problem you can run with LAMMPS. Most are 2d models so that they run quickly, requiring a few seconds to a few minutes to run on a desktop machine. Each problem has an input script (in.*) and produces a log file (log.*) and dump file (dump.*) when it runs. Some use a data file (data.*) of initial coordinates as additional input.

A few sample log file outputs on different machines and different numbers of processors are included in the directories to compare your answers to. E.g. a log file like log.crack.date.foo.P means it ran on P processors of machine "foo" with the dated version of LAMMPS. Note that these problems should get statistically similar answers when run on different machines or different numbers of processors, but not identical answers to those in the log of dump files included here. See the Errors section of the LAMMPS documentation for more discussion.

The dump files produced by the example runs can be animated using the xmovie tool described in the "Additional Tools" section of the LAMMPS documentation. Animations of many of these examples can be viewed on the Movies section of the LAMMPS WWW Site.

These are the sample problems and their output in the various sub-directories:

colloid: big colloid particles in a small particle solvent, 2d system comb: models using the COMB potential crack: crack propagation in a 2d solid dipole: point dipolar particles, 2d system eim: NaCl using the EIM potential ellipse: ellipsoidal particles in spherical solvent, 2d system flow: Couette and Poiseuille flow in a 2d channel friction: frictional contact of spherical asperities between 2d surfaces indent: spherical indenter into a 2d solid meam: MEAM test for SiC and shear (same as shear examples) melt: rapid melt of 3d LJ system micelle: self-assembly of small lipid-like molecules into 2d bilayers min: energy minimization of 2d LJ melt msst: MSST shock dynamics neb: nudged elastic band (NEB) calculation for barrier finding nemd: non-equilibrium MD of 2d sheared system obstacle: flow around two voids in a 2d channel peptide: dynamics of a small solvated peptide chain (5-mer) peri: Peridynamic model of cylinder impacted by indenter pour: pouring of granular particles into a 3d box, then chute flow prd: parallel replica dynamics of vacancy diffusion in bulk Si reax: RDX and TATB models using the ReaxFF rigid: rigid bodies modeled as independent or coupled shear: sideways shear applied to 2d solid, with and without a void srd: stochastic rotation dynamics (SRD) particles as solvent tad: temperature-accelerated dynamics of vacancy diffusion in bulk Si

Here is how you might run and visualize one of the sample problems:

cd indent cp ../../src/lmp_linux . # copy LAMMPS executable to this dir lmp_linux < in.indent # run the problem

Running the simulation produces the files dump.indent and log.lammps. You can visualize the dump file as follows:

../../tools/xmovie/xmovie -scale dump.indent

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There is also an ELASTIC directory with an example script for computing elastic constants, using a zero temperature Si example. See the in.elastic file for more info.

There is also a USER directory which contains subdirectories of user-provided examples for user packages. See the README files in those directories for more info. See the doc/Section_start.html file for more info about user packages.