<!DOCTYPE html> <!--[if IE 8]><html class="no-js lt-ie9" lang="en" > <![endif]--> <!--[if gt IE 8]><!--> <html class="no-js" lang="en" > <!--<![endif]--> <head> <meta charset="utf-8"> <meta name="viewport" content="width=device-width, initial-scale=1.0"> <title>7. Example problems — LAMMPS 15 May 2015 version documentation</title> <link rel="stylesheet" href="_static/css/theme.css" type="text/css" /> <link rel="stylesheet" href="_static/sphinxcontrib-images/LightBox2/lightbox2/css/lightbox.css" type="text/css" /> <link rel="top" title="LAMMPS 15 May 2015 version documentation" href="index.html"/> <link rel="next" title="8. Performance & scalability" href="Section_perf.html"/> <link rel="prev" title="6. 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Example problems</li> <li class="wy-breadcrumbs-aside"> <a href="http://lammps.sandia.gov">Homepage</a> <a href="Section_commands.html#comm">Commands</a> </li> </ul> <hr/> </div> <div role="main" class="document" itemscope="itemscope" itemtype="http://schema.org/Article"> <div itemprop="articleBody"> <div class="section" id="example-problems"> <h1>7. Example problems<a class="headerlink" href="#example-problems" title="Permalink to this headline">ΒΆ</a></h1> <p>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”.</p> <p>For examples that use input data files, many of them were produced by <a class="reference external" href="http://pizza.sandia.gov">Pizza.py</a> or setup tools described in the <a class="reference internal" href="Section_tools.html"><em>Additional Tools</em></a> section of the LAMMPS documentation and provided with the LAMMPS distribution.</p> <p>If you uncomment the <a class="reference internal" href="dump.html"><em>dump</em></a> command in the input script, a text dump file will be produced, which can be animated by various <a class="reference external" href="http://lammps.sandia.gov/viz.html">visualization programs</a>. It can also be animated using the xmovie tool described in the <a class="reference internal" href="Section_tools.html"><em>Additional Tools</em></a> section of the LAMMPS documentation.</p> <p>If you uncomment the <a class="reference internal" href="dump.html"><em>dump image</em></a> command in the input script, and assuming you have built LAMMPS with a JPG library, JPG snapshot images will be produced when the simulation runs. They can be quickly post-processed into a movie using commands described on the <a class="reference internal" href="dump_image.html"><em>dump image</em></a> doc page.</p> <p>Animations of many of these examples can be viewed on the Movies section of the <a class="reference external" href="http://lammps.sandia.gov">LAMMPS WWW Site</a>.</p> <p>These are the sample problems in the examples sub-directories:</p> <table border="1" class="docutils"> <colgroup> <col width="15%" /> <col width="85%" /> </colgroup> <tbody valign="top"> <tr class="row-odd"><td>balance</td> <td>dynamic load balancing, 2d system</td> </tr> <tr class="row-even"><td>body</td> <td>body particles, 2d system</td> </tr> <tr class="row-odd"><td>colloid</td> <td>big colloid particles in a small particle solvent, 2d system</td> </tr> <tr class="row-even"><td>comb</td> <td>models using the COMB potential</td> </tr> <tr class="row-odd"><td>crack</td> <td>crack propagation in a 2d solid</td> </tr> <tr class="row-even"><td>cuda</td> <td>use of the USER-CUDA package for GPU acceleration</td> </tr> <tr class="row-odd"><td>dipole</td> <td>point dipolar particles, 2d system</td> </tr> <tr class="row-even"><td>dreiding</td> <td>methanol via Dreiding FF</td> </tr> <tr class="row-odd"><td>eim</td> <td>NaCl using the EIM potential</td> </tr> <tr class="row-even"><td>ellipse</td> <td>ellipsoidal particles in spherical solvent, 2d system</td> </tr> <tr class="row-odd"><td>flow</td> <td>Couette and Poiseuille flow in a 2d channel</td> </tr> <tr class="row-even"><td>friction</td> <td>frictional contact of spherical asperities between 2d surfaces</td> </tr> <tr class="row-odd"><td>gpu</td> <td>use of the GPU package for GPU acceleration</td> </tr> <tr class="row-even"><td>hugoniostat</td> <td>Hugoniostat shock dynamics</td> </tr> <tr class="row-odd"><td>indent</td> <td>spherical indenter into a 2d solid</td> </tr> <tr class="row-even"><td>intel</td> <td>use of the USER-INTEL package for CPU or Intel(R) Xeon Phi(TM) coprocessor</td> </tr> <tr class="row-odd"><td>kim</td> <td>use of potentials in Knowledge Base for Interatomic Models (KIM)</td> </tr> <tr class="row-even"><td>line</td> <td>line segment particles in 2d rigid bodies</td> </tr> <tr class="row-odd"><td>meam</td> <td>MEAM test for SiC and shear (same as shear examples)</td> </tr> <tr class="row-even"><td>melt</td> <td>rapid melt of 3d LJ system</td> </tr> <tr class="row-odd"><td>micelle</td> <td>self-assembly of small lipid-like molecules into 2d bilayers</td> </tr> <tr class="row-even"><td>min</td> <td>energy minimization of 2d LJ melt</td> </tr> <tr class="row-odd"><td>msst</td> <td>MSST shock dynamics</td> </tr> <tr class="row-even"><td>nb3b</td> <td>use of nonbonded 3-body harmonic pair style</td> </tr> <tr class="row-odd"><td>neb</td> <td>nudged elastic band (NEB) calculation for barrier finding</td> </tr> <tr class="row-even"><td>nemd</td> <td>non-equilibrium MD of 2d sheared system</td> </tr> <tr class="row-odd"><td>obstacle</td> <td>flow around two voids in a 2d channel</td> </tr> <tr class="row-even"><td>peptide</td> <td>dynamics of a small solvated peptide chain (5-mer)</td> </tr> <tr class="row-odd"><td>peri</td> <td>Peridynamic model of cylinder impacted by indenter</td> </tr> <tr class="row-even"><td>pour</td> <td>pouring of granular particles into a 3d box, then chute flow</td> </tr> <tr class="row-odd"><td>prd</td> <td>parallel replica dynamics of vacancy diffusion in bulk Si</td> </tr> <tr class="row-even"><td>qeq</td> <td>use of the QEQ pacakge for charge equilibration</td> </tr> <tr class="row-odd"><td>reax</td> <td>RDX and TATB models using the ReaxFF</td> </tr> <tr class="row-even"><td>rigid</td> <td>rigid bodies modeled as independent or coupled</td> </tr> <tr class="row-odd"><td>shear</td> <td>sideways shear applied to 2d solid, with and without a void</td> </tr> <tr class="row-even"><td>snap</td> <td>NVE dynamics for BCC tantalum crystal using SNAP potential</td> </tr> <tr class="row-odd"><td>srd</td> <td>stochastic rotation dynamics (SRD) particles as solvent</td> </tr> <tr class="row-even"><td>tad</td> <td>temperature-accelerated dynamics of vacancy diffusion in bulk Si</td> </tr> <tr class="row-odd"><td>tri</td> <td>triangular particles in rigid bodies</td> </tr> </tbody> </table> <p>Here is how you might run and visualize one of the sample problems:</p> <div class="highlight-python"><div class="highlight"><pre>cd indent cp ../../src/lmp_linux . # copy LAMMPS executable to this dir lmp_linux < in.indent # run the problem </pre></div> </div> <p>Running the simulation produces the files <em>dump.indent</em> and <em>log.lammps</em>. You can visualize the dump file as follows:</p> <div class="highlight-python"><div class="highlight"><pre>../../tools/xmovie/xmovie -scale dump.indent </pre></div> </div> <p>If you uncomment the <a class="reference internal" href="dump_image.html"><em>dump image</em></a> line(s) in the input script a series of JPG images will be produced by the run. These can be viewed individually or turned into a movie or animated by tools like ImageMagick or QuickTime or various Windows-based tools. See the <a class="reference internal" href="dump_image.html"><em>dump image</em></a> doc page for more details. E.g. this Imagemagick command would create a GIF file suitable for viewing in a browser.</p> <div class="highlight-python"><div class="highlight"><pre>% convert -loop 1 *.jpg foo.gif </pre></div> </div> <hr class="docutils" /> <p>There is also a COUPLE directory with examples of how to use LAMMPS as a library, either by itself or in tandem with another code or library. See the COUPLE/README file to get started.</p> <p>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.</p> <p>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 <a class="reference internal" href="Section_start.html"><em>Section_start.html</em></a> file for more info about user packages.</p> </div> </div> </div> <footer> <div class="rst-footer-buttons" role="navigation" aria-label="footer navigation"> <a href="Section_perf.html" class="btn btn-neutral float-right" title="8. Performance & scalability" accesskey="n">Next <span class="fa fa-arrow-circle-right"></span></a> <a href="Section_howto.html" class="btn btn-neutral" title="6. 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