2006-09-22 00:22:34 +08:00
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"Previous Section"_Section_howto.html - "LAMMPS WWW Site"_lws - "LAMMPS Documentation"_ld - "LAMMPS Commands"_lc - "Next Section"_Section_perf.html :c
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:link(lws,http://lammps.sandia.gov)
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:link(ld,Manual.html)
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:link(lc,Section_commands.html#comm)
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:line
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5. Example problems :h3
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The LAMMPS distribution includes an examples sub-directory with
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several sample problems. Each problem is in a sub-directory of its
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own. Most are 2d models so that they run quickly, requiring at most a
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couple of minutes to run on a desktop machine. Each problem has an
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input script (in.*) and produces a log file (log.*) and dump file
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(dump.*) when it runs. Some use a data file (data.*) of initial
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coordinates as additional input. A few sample log file outputs on
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different machines and different numbers of processors are included in
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the directories to compare your answers to. E.g. a log file like
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log.crack.foo.P means it ran on P processors of machine "foo".
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The dump files produced by the example runs can be animated using the
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xmovie tool described in the "Tools section"_Section_tools.html. MPEG
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versions of most of the xmovie animations are also viewable from the
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Examples page of the "LAMMPS WWW Site"_lws.
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These are the sample problems in the examples sub-directories:
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crack: crack propagation in a 2d solid
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2006-09-28 22:50:55 +08:00
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flow: Couette and Poiseuille flow in a 2d channel
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2006-09-22 00:22:34 +08:00
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friction: frictional contact of spherical asperities between 2d surfaces
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indent: spherical indenter into a 2d solid
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melt: rapid melt of 3d LJ system
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micelle: self-assembly of small lipid-like molecules into 2d bilayers
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min: energy minimization of 2d LJ melt
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obstacle: flow around two voids in a 2d channel
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peptide: dynamics of a small solvated peptide chain (5-mer)
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pour: pouring of granular particles into a 3d box, then chute flow
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rigid: rigid bodies modeled as independent or coupled
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shear: sideways shear applied to 2d solid, with and without a void :tb(s=:)
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Here is how you might run and visualize one of the sample problems:
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cd indent
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cp ../../src/lmp_linux . # copy LAMMPS executable to this dir
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lmp_linux < in.indent # run the problem :pre
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Running the simulation produces the files {dump.indent} and
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{log.lammps}. You can visualize the dump file as follows:
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../../tools/xmovie/xmovie -scale dump.indent :pre
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There is also a directory "couple" in the examples sub-directory,
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which contains a stand-alone code umbrella.cpp that links LAMMPS as a
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library. The README describes how to build the code. The code itself
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runs LAMMPS on a subset of processors, sets up a LAMMPS problem
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by invoking LAMMPS input script commands one at a time, does
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a run, grabs atom coordinates, changes one atom position, puts
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them back into LAMMPS, and does another run.
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This illustrates how an umbrella code could include new models and
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physics while using LAMMPS to perform MD, or how the umbrella code
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could call both LAMMPS and some other code to perform a coupled
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calculation.
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