Homec4science
Diffusion lammps (efficient_neuronet) Browse

lammps/doc/html/mass.html
7baaf2dfe210efficient_neuronet

Last Change
Raw File

mass.html
View Options

<!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>mass command &mdash; LAMMPS 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 documentation" href="index.html"/>
<script src="_static/js/modernizr.min.js"></script>
</head>
<body class="wy-body-for-nav" role="document">
<div class="wy-grid-for-nav">
<nav data-toggle="wy-nav-shift" class="wy-nav-side">
<div class="wy-side-nav-search">
<a href="Manual.html" class="icon icon-home"> LAMMPS
</a>
<div role="search">
<form id="rtd-search-form" class="wy-form" action="search.html" method="get">
<input type="text" name="q" placeholder="Search docs" />
<input type="hidden" name="check_keywords" value="yes" />
<input type="hidden" name="area" value="default" />
</form>
</div>
</div>
<div class="wy-menu wy-menu-vertical" data-spy="affix" role="navigation" aria-label="main navigation">
<ul>
<li class="toctree-l1"><a class="reference internal" href="Section_intro.html">1. Introduction</a></li>
<li class="toctree-l1"><a class="reference internal" href="Section_start.html">2. Getting Started</a></li>
<li class="toctree-l1"><a class="reference internal" href="Section_commands.html">3. Commands</a></li>
<li class="toctree-l1"><a class="reference internal" href="Section_packages.html">4. Packages</a></li>
<li class="toctree-l1"><a class="reference internal" href="Section_accelerate.html">5. Accelerating LAMMPS performance</a></li>
<li class="toctree-l1"><a class="reference internal" href="Section_howto.html">6. How-to discussions</a></li>
<li class="toctree-l1"><a class="reference internal" href="Section_example.html">7. Example problems</a></li>
<li class="toctree-l1"><a class="reference internal" href="Section_perf.html">8. Performance &amp; scalability</a></li>
<li class="toctree-l1"><a class="reference internal" href="Section_tools.html">9. Additional tools</a></li>
<li class="toctree-l1"><a class="reference internal" href="Section_modify.html">10. Modifying &amp; extending LAMMPS</a></li>
<li class="toctree-l1"><a class="reference internal" href="Section_python.html">11. Python interface to LAMMPS</a></li>
<li class="toctree-l1"><a class="reference internal" href="Section_errors.html">12. Errors</a></li>
<li class="toctree-l1"><a class="reference internal" href="Section_history.html">13. Future and history</a></li>
</ul>
</div>
&nbsp;
</nav>
<section data-toggle="wy-nav-shift" class="wy-nav-content-wrap">
<nav class="wy-nav-top" role="navigation" aria-label="top navigation">
<i data-toggle="wy-nav-top" class="fa fa-bars"></i>
<a href="Manual.html">LAMMPS</a>
</nav>
<div class="wy-nav-content">
<div class="rst-content">
<div role="navigation" aria-label="breadcrumbs navigation">
<ul class="wy-breadcrumbs">
<li><a href="Manual.html">Docs</a> &raquo;</li>
<li>mass command</li>
<li class="wy-breadcrumbs-aside">
<a href="http://lammps.sandia.gov">Website</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="mass-command">
<span id="index-0"></span><h1>mass command</h1>
<div class="section" id="syntax">
<h2>Syntax</h2>
<div class="highlight-default"><div class="highlight"><pre><span></span><span class="n">mass</span> <span class="n">I</span> <span class="n">value</span>
</pre></div>
</div>
<ul class="simple">
<li>I = atom type (see asterisk form below)</li>
<li>value = mass</li>
</ul>
</div>
<div class="section" id="examples">
<h2>Examples</h2>
<div class="highlight-default"><div class="highlight"><pre><span></span><span class="n">mass</span> <span class="mi">1</span> <span class="mf">1.0</span>
<span class="n">mass</span> <span class="o">*</span> <span class="mf">62.5</span>
<span class="n">mass</span> <span class="mi">2</span><span class="o">*</span> <span class="mf">62.5</span>
</pre></div>
</div>
</div>
<div class="section" id="description">
<h2>Description</h2>
<p>Set the mass for all atoms of one or more atom types. Per-type mass
values can also be set in the <a class="reference internal" href="read_data.html"><span class="doc">read_data</span></a> data file
using the &#8220;Masses&#8221; keyword. See the <span class="xref doc">units</span> command for
what mass units to use.</p>
<p>The I index can be specified in one of two ways. An explicit numeric
value can be used, as in the 1st example above. Or a wild-card
asterisk can be used to set the mass for multiple atom types. This
takes the form &#8220;*&#8221; or &#8220;<em>n&#8221; or &#8220;n</em>&#8221; or &#8220;m*n&#8221;. If N = the number of
atom types, then an asterisk with no numeric values means all types
from 1 to N. A leading asterisk means all types from 1 to n
(inclusive). A trailing asterisk means all types from n to N
(inclusive). A middle asterisk means all types from m to n
(inclusive).</p>
<p>A line in a <a class="reference internal" href="read_data.html"><span class="doc">data file</span></a> that follows the &#8220;Masses&#8221;
keyword specifies mass using the same format as the arguments of the
mass command in an input script, except that no wild-card asterisk can
be used. For example, under the &#8220;Masses&#8221; section of a data file, the
line that corresponds to the 1st example above would be listed as</p>
<div class="highlight-default"><div class="highlight"><pre><span></span><span class="mi">1</span> <span class="mf">1.0</span>
</pre></div>
</div>
<p>Note that the mass command can only be used if the <a class="reference internal" href="atom_style.html"><span class="doc">atom style</span></a> requires per-type atom mass to be set.
Currently, all but the <em>sphere</em> and <em>ellipsoid</em> and <em>peri</em> styles do.
They require mass to be set for individual particles, not types.
Per-atom masses are defined in the data file read by the
<a class="reference internal" href="read_data.html"><span class="doc">read_data</span></a> command, or set to default values by the
<a class="reference internal" href="create_atoms.html"><span class="doc">create_atoms</span></a> command. Per-atom masses can also be
set to new values by the <a class="reference internal" href="set.html"><span class="doc">set mass</span></a> or <a class="reference internal" href="set.html"><span class="doc">set density</span></a>
commands.</p>
<p>Also note that <a class="reference internal" href="pair_eam.html"><span class="doc">pair_style eam</span></a> and <a class="reference internal" href="pair_bop.html"><span class="doc">pair_style bop</span></a> commands define the masses of atom types in their
respective potential files, in which case the mass command is normally
not used.</p>
<p>If you define a <a class="reference internal" href="atom_style.html"><span class="doc">hybrid atom style</span></a> which includes one
(or more) sub-styles which require per-type mass and one (or more)
sub-styles which require per-atom mass, then you must define both.
However, in this case the per-type mass will be ignored; only the
per-atom mass will be used by LAMMPS.</p>
</div>
<div class="section" id="restrictions">
<h2>Restrictions</h2>
<p>This command must come after the simulation box is defined by a
<a class="reference internal" href="read_data.html"><span class="doc">read_data</span></a>, <a class="reference internal" href="read_restart.html"><span class="doc">read_restart</span></a>, or
<a class="reference internal" href="create_box.html"><span class="doc">create_box</span></a> command.</p>
<p>All masses must be defined before a simulation is run. They must also
all be defined before a <a class="reference internal" href="velocity.html"><span class="doc">velocity</span></a> or <a class="reference internal" href="fix_shake.html"><span class="doc">fix shake</span></a> command is used.</p>
<p>The mass assigned to any type or atom must be &gt; 0.0.</p>
<p><strong>Related commands:</strong> none</p>
<p><strong>Default:</strong> none</p>
</div>
</div>
</div>
</div>
<footer>
<hr/>
<div role="contentinfo">
<p>
&copy; Copyright 2013 Sandia Corporation.
</p>
</div>
Built with <a href="http://sphinx-doc.org/">Sphinx</a> using a <a href="https://github.com/snide/sphinx_rtd_theme">theme</a> provided by <a href="https://readthedocs.org">Read the Docs</a>.
</footer>
</div>
</div>
</section>
</div>
<script type="text/javascript">
var DOCUMENTATION_OPTIONS = {
URL_ROOT:'./',
VERSION:'',
COLLAPSE_INDEX:false,
FILE_SUFFIX:'.html',
HAS_SOURCE: true
};
</script>
<script type="text/javascript" src="_static/jquery.js"></script>
<script type="text/javascript" src="_static/underscore.js"></script>
<script type="text/javascript" src="_static/doctools.js"></script>
<script type="text/javascript" src="https://cdn.mathjax.org/mathjax/latest/MathJax.js?config=TeX-AMS-MML_HTMLorMML"></script>
<script type="text/javascript" src="_static/sphinxcontrib-images/LightBox2/lightbox2/js/jquery-1.11.0.min.js"></script>
<script type="text/javascript" src="_static/sphinxcontrib-images/LightBox2/lightbox2/js/lightbox.min.js"></script>
<script type="text/javascript" src="_static/sphinxcontrib-images/LightBox2/lightbox2-customize/jquery-noconflict.js"></script>
<script type="text/javascript" src="_static/js/theme.js"></script>
<script type="text/javascript">
jQuery(function () {
SphinxRtdTheme.StickyNav.enable();
});
</script>
</body>
</html>
c4science · Help