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### 5. Example problems

The LAMMPS distribution includes an examples sub-directory with several sample problems. Each problem is in a sub-directory of its own. Most are 2d models so that they run quickly, requiring at most a couple of 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.foo.P means it ran on P processors of machine "foo".

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 in the examples 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 a 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

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

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.