586 lines
43 KiB
HTML
586 lines
43 KiB
HTML
<!DOCTYPE html>
|
|
<html class="writer-html5" lang="en" >
|
|
<head>
|
|
<meta charset="utf-8" /><meta name="viewport" content="width=device-width, initial-scale=1" />
|
|
|
|
<meta name="viewport" content="width=device-width, initial-scale=1.0" />
|
|
<title>pair_modify command — LAMMPS documentation</title>
|
|
<link rel="stylesheet" href="_static/pygments.css" type="text/css" />
|
|
<link rel="stylesheet" href="_static/css/theme.css" type="text/css" />
|
|
<link rel="stylesheet" href="_static/sphinx-design.min.css" type="text/css" />
|
|
<link rel="stylesheet" href="_static/css/lammps.css" type="text/css" />
|
|
<link rel="shortcut icon" href="_static/lammps.ico"/>
|
|
<link rel="canonical" href="https://docs.lammps.org/pair_modify.html" />
|
|
<!--[if lt IE 9]>
|
|
<script src="_static/js/html5shiv.min.js"></script>
|
|
<![endif]-->
|
|
|
|
<script src="_static/jquery.js?v=5d32c60e"></script>
|
|
<script src="_static/_sphinx_javascript_frameworks_compat.js?v=2cd50e6c"></script>
|
|
<script src="_static/documentation_options.js?v=5929fcd5"></script>
|
|
<script src="_static/doctools.js?v=9bcbadda"></script>
|
|
<script src="_static/sphinx_highlight.js?v=dc90522c"></script>
|
|
<script src="_static/design-tabs.js?v=f930bc37"></script>
|
|
<script async="async" src="_static/mathjax/es5/tex-mml-chtml.js?v=cadf963e"></script>
|
|
<script src="_static/js/theme.js"></script>
|
|
<link rel="index" title="Index" href="genindex.html" />
|
|
<link rel="search" title="Search" href="search.html" />
|
|
<link rel="next" title="pair_style command" href="pair_style.html" />
|
|
<link rel="prev" title="pair_coeff command" href="pair_coeff.html" />
|
|
</head>
|
|
|
|
<body class="wy-body-for-nav">
|
|
<div class="wy-grid-for-nav">
|
|
<nav data-toggle="wy-nav-shift" class="wy-nav-side">
|
|
<div class="wy-side-scroll">
|
|
<div class="wy-side-nav-search" >
|
|
|
|
|
|
|
|
<a href="Manual.html">
|
|
|
|
<img src="_static/lammps-logo.png" class="logo" alt="Logo"/>
|
|
</a>
|
|
<div class="lammps_version">Version: <b>19 Nov 2024</b></div>
|
|
<div class="lammps_release">git info: </div>
|
|
<div role="search">
|
|
<form id="rtd-search-form" class="wy-form" action="search.html" method="get">
|
|
<input type="text" name="q" placeholder="Search docs" aria-label="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="Navigation menu">
|
|
<p class="caption" role="heading"><span class="caption-text">User Guide</span></p>
|
|
<ul>
|
|
<li class="toctree-l1"><a class="reference internal" href="Intro.html">1. Introduction</a></li>
|
|
<li class="toctree-l1"><a class="reference internal" href="Install.html">2. Install LAMMPS</a></li>
|
|
<li class="toctree-l1"><a class="reference internal" href="Build.html">3. Build LAMMPS</a></li>
|
|
<li class="toctree-l1"><a class="reference internal" href="Run_head.html">4. Run LAMMPS</a></li>
|
|
<li class="toctree-l1"><a class="reference internal" href="Commands.html">5. Commands</a></li>
|
|
<li class="toctree-l1"><a class="reference internal" href="Packages.html">6. Optional packages</a></li>
|
|
<li class="toctree-l1"><a class="reference internal" href="Speed.html">7. Accelerate performance</a></li>
|
|
<li class="toctree-l1"><a class="reference internal" href="Howto.html">8. Howto discussions</a></li>
|
|
<li class="toctree-l1"><a class="reference internal" href="Examples.html">9. Example scripts</a></li>
|
|
<li class="toctree-l1"><a class="reference internal" href="Tools.html">10. Auxiliary tools</a></li>
|
|
<li class="toctree-l1"><a class="reference internal" href="Errors.html">11. Errors</a></li>
|
|
</ul>
|
|
<p class="caption" role="heading"><span class="caption-text">Programmer Guide</span></p>
|
|
<ul>
|
|
<li class="toctree-l1"><a class="reference internal" href="Library.html">1. LAMMPS Library Interfaces</a></li>
|
|
<li class="toctree-l1"><a class="reference internal" href="Python_head.html">2. Use Python with LAMMPS</a></li>
|
|
<li class="toctree-l1"><a class="reference internal" href="Modify.html">3. Modifying & extending LAMMPS</a></li>
|
|
<li class="toctree-l1"><a class="reference internal" href="Developer.html">4. Information for Developers</a></li>
|
|
</ul>
|
|
<p class="caption" role="heading"><span class="caption-text">Command Reference</span></p>
|
|
<ul class="current">
|
|
<li class="toctree-l1 current"><a class="reference internal" href="commands_list.html">Commands</a><ul class="current">
|
|
<li class="toctree-l2"><a class="reference internal" href="angle_coeff.html">angle_coeff command</a></li>
|
|
<li class="toctree-l2"><a class="reference internal" href="angle_style.html">angle_style command</a></li>
|
|
<li class="toctree-l2"><a class="reference internal" href="angle_write.html">angle_write command</a></li>
|
|
<li class="toctree-l2"><a class="reference internal" href="atom_modify.html">atom_modify command</a></li>
|
|
<li class="toctree-l2"><a class="reference internal" href="atom_style.html">atom_style command</a></li>
|
|
<li class="toctree-l2"><a class="reference internal" href="balance.html">balance command</a></li>
|
|
<li class="toctree-l2"><a class="reference internal" href="bond_coeff.html">bond_coeff command</a></li>
|
|
<li class="toctree-l2"><a class="reference internal" href="bond_style.html">bond_style command</a></li>
|
|
<li class="toctree-l2"><a class="reference internal" href="bond_write.html">bond_write command</a></li>
|
|
<li class="toctree-l2"><a class="reference internal" href="boundary.html">boundary command</a></li>
|
|
<li class="toctree-l2"><a class="reference internal" href="change_box.html">change_box command</a></li>
|
|
<li class="toctree-l2"><a class="reference internal" href="clear.html">clear command</a></li>
|
|
<li class="toctree-l2"><a class="reference internal" href="comm_modify.html">comm_modify command</a></li>
|
|
<li class="toctree-l2"><a class="reference internal" href="comm_style.html">comm_style command</a></li>
|
|
<li class="toctree-l2"><a class="reference internal" href="compute.html">compute command</a></li>
|
|
<li class="toctree-l2"><a class="reference internal" href="compute_modify.html">compute_modify command</a></li>
|
|
<li class="toctree-l2"><a class="reference internal" href="create_atoms.html">create_atoms command</a></li>
|
|
<li class="toctree-l2"><a class="reference internal" href="create_bonds.html">create_bonds command</a></li>
|
|
<li class="toctree-l2"><a class="reference internal" href="create_box.html">create_box command</a></li>
|
|
<li class="toctree-l2"><a class="reference internal" href="delete_atoms.html">delete_atoms command</a></li>
|
|
<li class="toctree-l2"><a class="reference internal" href="delete_bonds.html">delete_bonds command</a></li>
|
|
<li class="toctree-l2"><a class="reference internal" href="dielectric.html">dielectric command</a></li>
|
|
<li class="toctree-l2"><a class="reference internal" href="dihedral_coeff.html">dihedral_coeff command</a></li>
|
|
<li class="toctree-l2"><a class="reference internal" href="dihedral_style.html">dihedral_style command</a></li>
|
|
<li class="toctree-l2"><a class="reference internal" href="dihedral_write.html">dihedral_write command</a></li>
|
|
<li class="toctree-l2"><a class="reference internal" href="dimension.html">dimension command</a></li>
|
|
<li class="toctree-l2"><a class="reference internal" href="displace_atoms.html">displace_atoms command</a></li>
|
|
<li class="toctree-l2"><a class="reference internal" href="dynamical_matrix.html">dynamical_matrix command</a></li>
|
|
<li class="toctree-l2"><a class="reference internal" href="echo.html">echo command</a></li>
|
|
<li class="toctree-l2"><a class="reference internal" href="fix.html">fix command</a></li>
|
|
<li class="toctree-l2"><a class="reference internal" href="fix_modify.html">fix_modify command</a></li>
|
|
<li class="toctree-l2"><a class="reference internal" href="fitpod_command.html">fitpod command</a></li>
|
|
<li class="toctree-l2"><a class="reference internal" href="geturl.html">geturl command</a></li>
|
|
<li class="toctree-l2"><a class="reference internal" href="group.html">group command</a></li>
|
|
<li class="toctree-l2"><a class="reference internal" href="group2ndx.html">group2ndx command</a></li>
|
|
<li class="toctree-l2"><a class="reference internal" href="group2ndx.html#ndx2group-command">ndx2group command</a></li>
|
|
<li class="toctree-l2"><a class="reference internal" href="hyper.html">hyper command</a></li>
|
|
<li class="toctree-l2"><a class="reference internal" href="if.html">if command</a></li>
|
|
<li class="toctree-l2"><a class="reference internal" href="improper_coeff.html">improper_coeff command</a></li>
|
|
<li class="toctree-l2"><a class="reference internal" href="improper_style.html">improper_style command</a></li>
|
|
<li class="toctree-l2"><a class="reference internal" href="include.html">include command</a></li>
|
|
<li class="toctree-l2"><a class="reference internal" href="info.html">info command</a></li>
|
|
<li class="toctree-l2"><a class="reference internal" href="jump.html">jump command</a></li>
|
|
<li class="toctree-l2"><a class="reference internal" href="kim_commands.html">kim command</a></li>
|
|
<li class="toctree-l2"><a class="reference internal" href="kspace_modify.html">kspace_modify command</a></li>
|
|
<li class="toctree-l2"><a class="reference internal" href="kspace_style.html">kspace_style command</a></li>
|
|
<li class="toctree-l2"><a class="reference internal" href="label.html">label command</a></li>
|
|
<li class="toctree-l2"><a class="reference internal" href="labelmap.html">labelmap command</a></li>
|
|
<li class="toctree-l2"><a class="reference internal" href="lattice.html">lattice command</a></li>
|
|
<li class="toctree-l2"><a class="reference internal" href="log.html">log command</a></li>
|
|
<li class="toctree-l2"><a class="reference internal" href="mass.html">mass command</a></li>
|
|
<li class="toctree-l2"><a class="reference internal" href="mdi.html">mdi command</a></li>
|
|
<li class="toctree-l2"><a class="reference internal" href="min_modify.html">min_modify command</a></li>
|
|
<li class="toctree-l2"><a class="reference internal" href="min_spin.html">min_style spin command</a></li>
|
|
<li class="toctree-l2"><a class="reference internal" href="min_spin.html#min-style-spin-cg-command">min_style spin/cg command</a></li>
|
|
<li class="toctree-l2"><a class="reference internal" href="min_spin.html#min-style-spin-lbfgs-command">min_style spin/lbfgs command</a></li>
|
|
<li class="toctree-l2"><a class="reference internal" href="min_style.html">min_style cg command</a></li>
|
|
<li class="toctree-l2"><a class="reference internal" href="min_style.html#min-style-hftn-command">min_style hftn command</a></li>
|
|
<li class="toctree-l2"><a class="reference internal" href="min_style.html#min-style-sd-command">min_style sd command</a></li>
|
|
<li class="toctree-l2"><a class="reference internal" href="min_style.html#min-style-quickmin-command">min_style quickmin command</a></li>
|
|
<li class="toctree-l2"><a class="reference internal" href="min_style.html#min-style-fire-command">min_style fire command</a></li>
|
|
<li class="toctree-l2"><a class="reference internal" href="min_style.html#min-style-spin-command"><span class="xref std std-doc">min_style spin</span> command</a></li>
|
|
<li class="toctree-l2"><a class="reference internal" href="min_style.html#min-style-spin-cg-command"><span class="xref std std-doc">min_style spin/cg</span> command</a></li>
|
|
<li class="toctree-l2"><a class="reference internal" href="min_style.html#min-style-spin-lbfgs-command"><span class="xref std std-doc">min_style spin/lbfgs</span> command</a></li>
|
|
<li class="toctree-l2"><a class="reference internal" href="minimize.html">minimize command</a></li>
|
|
<li class="toctree-l2"><a class="reference internal" href="molecule.html">molecule command</a></li>
|
|
<li class="toctree-l2"><a class="reference internal" href="neb.html">neb command</a></li>
|
|
<li class="toctree-l2"><a class="reference internal" href="neb_spin.html">neb/spin command</a></li>
|
|
<li class="toctree-l2"><a class="reference internal" href="neigh_modify.html">neigh_modify command</a></li>
|
|
<li class="toctree-l2"><a class="reference internal" href="neighbor.html">neighbor command</a></li>
|
|
<li class="toctree-l2"><a class="reference internal" href="newton.html">newton command</a></li>
|
|
<li class="toctree-l2"><a class="reference internal" href="next.html">next command</a></li>
|
|
<li class="toctree-l2"><a class="reference internal" href="package.html">package command</a></li>
|
|
<li class="toctree-l2"><a class="reference internal" href="pair_coeff.html">pair_coeff command</a></li>
|
|
<li class="toctree-l2 current"><a class="current reference internal" href="#">pair_modify command</a><ul>
|
|
<li class="toctree-l3"><a class="reference internal" href="#syntax">Syntax</a></li>
|
|
<li class="toctree-l3"><a class="reference internal" href="#examples">Examples</a></li>
|
|
<li class="toctree-l3"><a class="reference internal" href="#description">Description</a></li>
|
|
<li class="toctree-l3"><a class="reference internal" href="#restrictions">Restrictions</a></li>
|
|
<li class="toctree-l3"><a class="reference internal" href="#related-commands">Related commands</a></li>
|
|
<li class="toctree-l3"><a class="reference internal" href="#default">Default</a></li>
|
|
</ul>
|
|
</li>
|
|
<li class="toctree-l2"><a class="reference internal" href="pair_style.html">pair_style command</a></li>
|
|
<li class="toctree-l2"><a class="reference internal" href="pair_write.html">pair_write command</a></li>
|
|
<li class="toctree-l2"><a class="reference internal" href="partition.html">partition command</a></li>
|
|
<li class="toctree-l2"><a class="reference internal" href="plugin.html">plugin command</a></li>
|
|
<li class="toctree-l2"><a class="reference internal" href="prd.html">prd command</a></li>
|
|
<li class="toctree-l2"><a class="reference internal" href="print.html">print command</a></li>
|
|
<li class="toctree-l2"><a class="reference internal" href="processors.html">processors command</a></li>
|
|
<li class="toctree-l2"><a class="reference internal" href="python.html">python command</a></li>
|
|
<li class="toctree-l2"><a class="reference internal" href="quit.html">quit command</a></li>
|
|
<li class="toctree-l2"><a class="reference internal" href="read_data.html">read_data command</a></li>
|
|
<li class="toctree-l2"><a class="reference internal" href="read_dump.html">read_dump command</a></li>
|
|
<li class="toctree-l2"><a class="reference internal" href="read_restart.html">read_restart command</a></li>
|
|
<li class="toctree-l2"><a class="reference internal" href="region.html">region command</a></li>
|
|
<li class="toctree-l2"><a class="reference internal" href="replicate.html">replicate command</a></li>
|
|
<li class="toctree-l2"><a class="reference internal" href="rerun.html">rerun command</a></li>
|
|
<li class="toctree-l2"><a class="reference internal" href="reset_atoms.html">reset_atoms command</a></li>
|
|
<li class="toctree-l2"><a class="reference internal" href="reset_timestep.html">reset_timestep command</a></li>
|
|
<li class="toctree-l2"><a class="reference internal" href="restart.html">restart command</a></li>
|
|
<li class="toctree-l2"><a class="reference internal" href="run.html">run command</a></li>
|
|
<li class="toctree-l2"><a class="reference internal" href="run_style.html">run_style command</a></li>
|
|
<li class="toctree-l2"><a class="reference internal" href="set.html">set command</a></li>
|
|
<li class="toctree-l2"><a class="reference internal" href="shell.html">shell command</a></li>
|
|
<li class="toctree-l2"><a class="reference internal" href="special_bonds.html">special_bonds command</a></li>
|
|
<li class="toctree-l2"><a class="reference internal" href="suffix.html">suffix command</a></li>
|
|
<li class="toctree-l2"><a class="reference internal" href="tad.html">tad command</a></li>
|
|
<li class="toctree-l2"><a class="reference internal" href="temper.html">temper command</a></li>
|
|
<li class="toctree-l2"><a class="reference internal" href="temper_grem.html">temper/grem command</a></li>
|
|
<li class="toctree-l2"><a class="reference internal" href="temper_npt.html">temper/npt command</a></li>
|
|
<li class="toctree-l2"><a class="reference internal" href="thermo.html">thermo command</a></li>
|
|
<li class="toctree-l2"><a class="reference internal" href="thermo_modify.html">thermo_modify command</a></li>
|
|
<li class="toctree-l2"><a class="reference internal" href="thermo_style.html">thermo_style command</a></li>
|
|
<li class="toctree-l2"><a class="reference internal" href="third_order.html">third_order command</a></li>
|
|
<li class="toctree-l2"><a class="reference internal" href="timer.html">timer command</a></li>
|
|
<li class="toctree-l2"><a class="reference internal" href="timestep.html">timestep command</a></li>
|
|
<li class="toctree-l2"><a class="reference internal" href="uncompute.html">uncompute command</a></li>
|
|
<li class="toctree-l2"><a class="reference internal" href="undump.html">undump command</a></li>
|
|
<li class="toctree-l2"><a class="reference internal" href="unfix.html">unfix command</a></li>
|
|
<li class="toctree-l2"><a class="reference internal" href="units.html">units command</a></li>
|
|
<li class="toctree-l2"><a class="reference internal" href="variable.html">variable command</a></li>
|
|
<li class="toctree-l2"><a class="reference internal" href="velocity.html">velocity command</a></li>
|
|
<li class="toctree-l2"><a class="reference internal" href="write_coeff.html">write_coeff command</a></li>
|
|
<li class="toctree-l2"><a class="reference internal" href="write_data.html">write_data command</a></li>
|
|
<li class="toctree-l2"><a class="reference internal" href="write_dump.html">write_dump command</a></li>
|
|
<li class="toctree-l2"><a class="reference internal" href="write_restart.html">write_restart command</a></li>
|
|
</ul>
|
|
</li>
|
|
<li class="toctree-l1"><a class="reference internal" href="fixes.html">Fix Styles</a></li>
|
|
<li class="toctree-l1"><a class="reference internal" href="computes.html">Compute Styles</a></li>
|
|
<li class="toctree-l1"><a class="reference internal" href="pairs.html">Pair Styles</a></li>
|
|
<li class="toctree-l1"><a class="reference internal" href="bonds.html">Bond Styles</a></li>
|
|
<li class="toctree-l1"><a class="reference internal" href="angles.html">Angle Styles</a></li>
|
|
<li class="toctree-l1"><a class="reference internal" href="dihedrals.html">Dihedral Styles</a></li>
|
|
<li class="toctree-l1"><a class="reference internal" href="impropers.html">Improper Styles</a></li>
|
|
<li class="toctree-l1"><a class="reference internal" href="dumps.html">Dump Styles</a></li>
|
|
<li class="toctree-l1"><a class="reference internal" href="fix_modify_atc_commands.html">fix_modify AtC commands</a></li>
|
|
<li class="toctree-l1"><a class="reference internal" href="Bibliography.html">Bibliography</a></li>
|
|
</ul>
|
|
|
|
</div>
|
|
</div>
|
|
</nav>
|
|
|
|
<section data-toggle="wy-nav-shift" class="wy-nav-content-wrap"><nav class="wy-nav-top" aria-label="Mobile navigation menu" >
|
|
<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 style-external-links">
|
|
<div role="navigation" aria-label="Page navigation">
|
|
<ul class="wy-breadcrumbs">
|
|
<li><a href="Manual.html" class="icon icon-home" aria-label="Home"></a></li>
|
|
<li class="breadcrumb-item"><a href="commands_list.html">Commands</a></li>
|
|
<li class="breadcrumb-item active">pair_modify command</li>
|
|
<li class="wy-breadcrumbs-aside">
|
|
<a href="https://www.lammps.org"><img src="_static/lammps-logo.png" width="64" height="16" alt="LAMMPS Homepage"></a> | <a href="Commands_all.html">Commands</a>
|
|
</li>
|
|
</ul><div class="rst-breadcrumbs-buttons" role="navigation" aria-label="Sequential page navigation">
|
|
<a href="pair_coeff.html" class="btn btn-neutral float-left" title="pair_coeff command" accesskey="p"><span class="fa fa-arrow-circle-left" aria-hidden="true"></span> Previous</a>
|
|
<a href="pair_style.html" class="btn btn-neutral float-right" title="pair_style command" accesskey="n">Next <span class="fa fa-arrow-circle-right" aria-hidden="true"></span></a>
|
|
</div>
|
|
<hr/>
|
|
</div>
|
|
<div role="main" class="document" itemscope="itemscope" itemtype="http://schema.org/Article">
|
|
<div itemprop="articleBody">
|
|
|
|
<p><span class="math notranslate nohighlight">\(\renewcommand{\AA}{\text{Å}}\)</span></p>
|
|
<section id="pair-modify-command">
|
|
<span id="index-0"></span><h1>pair_modify command<a class="headerlink" href="#pair-modify-command" title="Link to this heading"></a></h1>
|
|
<section id="syntax">
|
|
<h2>Syntax<a class="headerlink" href="#syntax" title="Link to this heading"></a></h2>
|
|
<div class="highlight-LAMMPS notranslate"><div class="highlight"><pre><span></span><span class="k">pair_modify</span><span class="w"> </span><span class="n">keyword</span><span class="w"> </span><span class="n">values</span><span class="w"> </span><span class="n">...</span>
|
|
</pre></div>
|
|
</div>
|
|
<ul>
|
|
<li><p>one or more keyword/value pairs may be listed</p></li>
|
|
<li><p>keyword = <em>pair</em> or <em>shift</em> or <em>mix</em> or <em>table</em> or <em>table/disp</em> or <em>tabinner</em>
|
|
or <em>tabinner/disp</em> or <em>tail</em> or <em>compute</em> or <em>nofdotr</em> or <em>special</em> or
|
|
<em>compute/tally</em> or <em>neigh/trim</em></p>
|
|
<pre class="literal-block"><em>pair</em> value = sub-style N
|
|
sub-style = sub-style of <a class="reference internal" href="pair_hybrid.html"><span class="doc">pair hybrid</span></a>
|
|
N = which instance of sub-style (1 to M), only specify if sub-style is used multiple times
|
|
<em>mix</em> value = <em>geometric</em> or <em>arithmetic</em> or <em>sixthpower</em>
|
|
<em>shift</em> value = <em>yes</em> or <em>no</em>
|
|
<em>table</em> value = N
|
|
2^N = # of values in table
|
|
<em>table/disp</em> value = N
|
|
2^N = # of values in table
|
|
<em>tabinner</em> value = cutoff
|
|
cutoff = inner cutoff at which to begin table (distance units)
|
|
<em>tabinner/disp</em> value = cutoff
|
|
cutoff = inner cutoff at which to begin table (distance units)
|
|
<em>tail</em> value = <em>yes</em> or <em>no</em>
|
|
<em>compute</em> value = <em>yes</em> or <em>no</em>
|
|
<em>nofdotr</em> value = none
|
|
<em>special</em> values = which wt1 wt2 wt3
|
|
which = <em>lj/coul</em> or <em>lj</em> or <em>coul</em>
|
|
w1,w2,w3 = 1-2, 1-3, 1-4 weights from 0.0 to 1.0 inclusive
|
|
<em>compute/tally</em> value = <em>yes</em> or <em>no</em>
|
|
<em>neigh/trim</em> value = <em>yes</em> or <em>no</em></pre>
|
|
</li>
|
|
</ul>
|
|
</section>
|
|
<section id="examples">
|
|
<h2>Examples<a class="headerlink" href="#examples" title="Link to this heading"></a></h2>
|
|
<div class="highlight-LAMMPS notranslate"><div class="highlight"><pre><span></span><span class="k">pair_modify</span><span class="w"> </span><span class="n">shift</span><span class="w"> </span><span class="n">yes</span><span class="w"> </span><span class="n">mix</span><span class="w"> </span><span class="n">geometric</span>
|
|
<span class="k">pair_modify</span><span class="w"> </span><span class="n">tail</span><span class="w"> </span><span class="n">yes</span>
|
|
<span class="k">pair_modify</span><span class="w"> </span><span class="n">table</span><span class="w"> </span><span class="m">12</span>
|
|
<span class="k">pair_modify</span><span class="w"> </span><span class="n">pair</span><span class="w"> </span><span class="n">lj</span><span class="o">/</span><span class="n">cut</span><span class="w"> </span><span class="k">compute </span><span class="nv nv-Identifier">no</span>
|
|
<span class="nv nv-Identifier">pair_modify</span><span class="w"> </span><span class="n">pair</span><span class="w"> </span><span class="n">tersoff</span><span class="w"> </span><span class="n">compute</span><span class="o">/</span><span class="n">tally</span><span class="w"> </span><span class="n">no</span>
|
|
<span class="k">pair_modify</span><span class="w"> </span><span class="n">pair</span><span class="w"> </span><span class="n">lj</span><span class="o">/</span><span class="n">cut</span><span class="o">/</span><span class="n">coul</span><span class="o">/</span><span class="n">long</span><span class="w"> </span><span class="m">1</span><span class="w"> </span><span class="n">special</span><span class="w"> </span><span class="n">lj</span><span class="o">/</span><span class="n">coul</span><span class="w"> </span><span class="m">0.0</span><span class="w"> </span><span class="m">0.0</span><span class="w"> </span><span class="m">0.0</span>
|
|
<span class="k">pair_modify</span><span class="w"> </span><span class="n">pair</span><span class="w"> </span><span class="n">lj</span><span class="o">/</span><span class="n">cut</span><span class="o">/</span><span class="n">coul</span><span class="o">/</span><span class="n">long</span><span class="w"> </span><span class="n">special</span><span class="w"> </span><span class="n">lj</span><span class="w"> </span><span class="m">0.0</span><span class="w"> </span><span class="m">0.0</span><span class="w"> </span><span class="m">0.5</span><span class="w"> </span><span class="n">special</span><span class="w"> </span><span class="n">coul</span><span class="w"> </span><span class="m">0.0</span><span class="w"> </span><span class="m">0.0</span><span class="w"> </span><span class="m">0.8333333</span>
|
|
</pre></div>
|
|
</div>
|
|
</section>
|
|
<section id="description">
|
|
<h2>Description<a class="headerlink" href="#description" title="Link to this heading"></a></h2>
|
|
<p>Modify the parameters of the currently defined pair style. If the
|
|
pair style is <a class="reference internal" href="pair_hybrid.html"><span class="doc">hybrid or hybrid/overlay</span></a>, then the
|
|
specified parameters are by default modified for all the hybrid sub-styles.</p>
|
|
<div class="admonition note">
|
|
<p class="admonition-title">Note</p>
|
|
<p>The behavior for hybrid pair styles can be changed by using the <em>pair</em>
|
|
keyword, which allows selection of a specific sub-style to apply all
|
|
remaining keywords to.
|
|
The <em>special</em> and <em>compute/tally</em> keywords can <strong>only</strong> be
|
|
used in conjunction with the <em>pair</em> keyword. See further details about
|
|
these 3 keywords below.</p>
|
|
</div>
|
|
<p>The <em>mix</em> keyword affects pair coefficients for interactions between
|
|
atoms of type I and J, when I != J and the coefficients are not
|
|
explicitly set in the input script. Note that coefficients for I = J
|
|
must be set explicitly, either in the input script via the
|
|
<a class="reference internal" href="pair_coeff.html"><span class="doc">pair_coeff</span></a> command or in the “Pair Coeffs” or “PairIJ Coeffs”
|
|
sections of the <a class="reference internal" href="read_data.html"><span class="doc">data file</span></a>. For some pair styles it is not
|
|
necessary to specify coefficients when I != J, since a “mixing” rule
|
|
will create them from the I,I and J,J settings. The pair_modify
|
|
<em>mix</em> value determines what formulas are used to compute the mixed
|
|
coefficients. In each case, the cutoff distance is mixed the same way
|
|
as sigma.</p>
|
|
<p>Note that not all pair styles support mixing and some mix options are
|
|
not available for certain pair styles. Also, there are additional
|
|
restrictions when using <a class="reference internal" href="pair_hybrid.html"><span class="doc">pair style hybrid or hybrid/overlay</span></a>. See the page for individual pair styles for those
|
|
restrictions. Note also that the <a class="reference internal" href="pair_coeff.html"><span class="doc">pair_coeff</span></a> command
|
|
also can be used to directly set coefficients for a specific I != J
|
|
pairing, in which case no mixing is performed. If possible, LAMMPS will
|
|
print an informational message about how many of the mixed pair
|
|
coefficients were generated and which mixing rule was applied.</p>
|
|
<ul>
|
|
<li><p>mix <em>geometric</em></p>
|
|
<div class="math notranslate nohighlight">
|
|
\[\begin{split}\epsilon_{ij} = & \sqrt{\epsilon_i \epsilon_j} \\
|
|
\sigma_{ij} = & \sqrt{\sigma_i \sigma_j}\end{split}\]</div>
|
|
</li>
|
|
<li><p>mix <em>arithmetic</em></p>
|
|
<div class="math notranslate nohighlight">
|
|
\[\begin{split}\epsilon_{ij} = & \sqrt{\epsilon_i \epsilon_j} \\
|
|
\sigma_{ij} = & \frac{1}{2} (\sigma_i + \sigma_j)\end{split}\]</div>
|
|
</li>
|
|
<li><p>mix <em>sixthpower</em></p>
|
|
<div class="math notranslate nohighlight">
|
|
\[\begin{split}\epsilon_{ij} = & \frac{2 \sqrt{\epsilon_i \epsilon_j} \sigma_i^3 \sigma_j^3}{\sigma_i^6 + \sigma_j^6} \\
|
|
\sigma_{ij} = & \left(\frac{1}{2} (\sigma_i^6 + \sigma_j^6) \right)^{\frac{1}{6}}\end{split}\]</div>
|
|
</li>
|
|
</ul>
|
|
<p>The <em>shift</em> keyword determines whether a Lennard-Jones potential is
|
|
shifted at its cutoff to 0.0. If so, this adds an energy term to each
|
|
pairwise interaction which will be included in the thermodynamic
|
|
output, but does not affect pair forces or atom trajectories. See the
|
|
doc page for individual pair styles to see which ones support this
|
|
option.</p>
|
|
<p>The <em>table</em> and <em>table/disp</em> keywords apply to pair styles with a
|
|
long-range Coulombic term or long-range dispersion term respectively;
|
|
see the page for individual styles to see which potentials support
|
|
these options. If N is non-zero, a table of length 2^N is
|
|
pre-computed for forces and energies, which can shrink their
|
|
computational cost by up to a factor of 2. The table is indexed via a
|
|
bit-mapping technique <a class="reference internal" href="#wolff1"><span class="std std-ref">(Wolff)</span></a> and a linear
|
|
interpolation is performed between adjacent table values. In our
|
|
experiments with different table styles (lookup, linear, spline), this
|
|
method typically gave the best performance in terms of speed and
|
|
accuracy.</p>
|
|
<p>The choice of table length is a tradeoff in accuracy versus speed. A
|
|
larger N yields more accurate force computations, but requires more
|
|
memory which can slow down the computation due to cache misses. A
|
|
reasonable value of N is between 8 and 16. The default value of 12
|
|
(table of length 4096) gives approximately the same accuracy as the
|
|
no-table (N = 0) option. For N = 0, forces and energies are computed
|
|
directly, using a polynomial fit for the needed erfc() function
|
|
evaluation, which is what earlier versions of LAMMPS did. Values
|
|
greater than 16 typically slow down the simulation and will not
|
|
improve accuracy; values from 1 to 8 give unreliable results.</p>
|
|
<p>The <em>tabinner</em> and <em>tabinner/disp</em> keywords set an inner cutoff above
|
|
which the pairwise computation is done by table lookup (if tables are
|
|
invoked), for the corresponding Coulombic and dispersion tables
|
|
discussed with the <em>table</em> and <em>table/disp</em> keywords. The smaller the
|
|
cutoff is set, the less accurate the table becomes (for a given number
|
|
of table values), which can require use of larger tables. The default
|
|
cutoff value is sqrt(2.0) distance units which means nearly all
|
|
pairwise interactions are computed via table lookup for simulations
|
|
with “real” units, but some close pairs may be computed directly
|
|
(non-table) for simulations with “lj” units.</p>
|
|
<p>When the <em>tail</em> keyword is set to <em>yes</em>, certain pair styles will
|
|
add a long-range VanderWaals tail “correction” to the energy and
|
|
pressure. These corrections are bookkeeping terms which do not affect
|
|
dynamics, unless a constant-pressure simulation is being performed.
|
|
See the page for individual styles to see which support this
|
|
option. These corrections are included in the calculation and
|
|
printing of thermodynamic quantities (see the <a class="reference internal" href="thermo_style.html"><span class="doc">thermo_style</span></a> command). Their effect will also be included in
|
|
constant NPT or NPH simulations where the pressure influences the
|
|
simulation box dimensions (e.g. the <a class="reference internal" href="fix_nh.html"><span class="doc">fix npt</span></a> and
|
|
<a class="reference internal" href="fix_nh.html"><span class="doc">fix nph</span></a> commands). The formulas used for the
|
|
long-range corrections come from equation 5 of <a class="reference internal" href="#sun"><span class="std std-ref">(Sun)</span></a>.</p>
|
|
<div class="admonition note">
|
|
<p class="admonition-title">Note</p>
|
|
<p>The tail correction terms are computed at the beginning of each
|
|
run, using the current atom counts of each atom type. If atoms are
|
|
deleted (or lost) or created during a simulation, e.g. via the
|
|
<a class="reference internal" href="fix_gcmc.html"><span class="doc">fix gcmc</span></a> command, the correction factors are not
|
|
re-computed. If you expect the counts to change dramatically, you
|
|
can break a run into a series of shorter runs so that the
|
|
correction factors are re-computed more frequently.</p>
|
|
</div>
|
|
<p>Several additional assumptions are inherent in using tail corrections,
|
|
including the following:</p>
|
|
<ul>
|
|
<li><p>The simulated system is a 3d bulk homogeneous liquid. This option
|
|
should not be used for systems that are non-liquid, 2d, have a slab
|
|
geometry (only 2d periodic), or inhomogeneous.</p></li>
|
|
<li><p>G(r), the radial distribution function (rdf), is unity beyond the
|
|
cutoff, so a fairly large cutoff should be used (i.e. 2.5 sigma for
|
|
an LJ fluid), and it is probably a good idea to verify this
|
|
assumption by checking the rdf. The rdf is not exactly unity beyond
|
|
the cutoff for each pair of interaction types, so the tail
|
|
correction is necessarily an approximation.</p>
|
|
<p>The tail corrections are computed at the beginning of each
|
|
simulation run. If the number of atoms changes during the run,
|
|
e.g. due to atoms leaving the simulation domain, or use of the
|
|
<a class="reference internal" href="fix_gcmc.html"><span class="doc">fix gcmc</span></a> command, then the corrections are not
|
|
updated to reflect the changed atom count. If this is a large
|
|
effect in your simulation, you should break the long run into
|
|
several short runs, so that the correction factors are re-computed
|
|
multiple times.</p>
|
|
</li>
|
|
<li><p>Thermophysical properties obtained from calculations with this
|
|
option enabled will not be thermodynamically consistent with the
|
|
truncated force-field that was used. In other words, atoms do not
|
|
feel any LJ pair interactions beyond the cutoff, but the energy and
|
|
pressure reported by the simulation include an estimated
|
|
contribution from those interactions.</p></li>
|
|
</ul>
|
|
<p>The <em>compute</em> keyword allows pairwise computations to be turned off,
|
|
even though a <a class="reference internal" href="pair_style.html"><span class="doc">pair_style</span></a> is defined. This is not
|
|
useful for running a real simulation, but can be useful for debugging
|
|
purposes or for performing a <a class="reference internal" href="rerun.html"><span class="doc">rerun</span></a> simulation, when you
|
|
only wish to compute partial forces that do not include the pairwise
|
|
contribution.</p>
|
|
<p>Two examples are as follows. First, this option allows you to perform
|
|
a simulation with <a class="reference internal" href="pair_hybrid.html"><span class="doc">pair_style hybrid</span></a> with only a
|
|
subset of the hybrid sub-styles enabled. Second, this option allows
|
|
you to perform a simulation with only long-range interactions but no
|
|
short-range pairwise interactions. Doing this by simply not defining
|
|
a pair style will not work, because the <a class="reference internal" href="kspace_style.html"><span class="doc">kspace_style</span></a> command requires a Kspace-compatible pair style be
|
|
defined.</p>
|
|
<p>The <em>nofdotr</em> keyword allows to disable an optimization that computes
|
|
the global stress tensor from the total forces and atom positions
|
|
rather than from summing forces between individual pairs of atoms.</p>
|
|
<hr class="docutils" />
|
|
<p>The <em>pair</em> keyword can only be used with the <a class="reference internal" href="pair_hybrid.html"><span class="doc">hybrid and
|
|
hybrid/overlay</span></a> pair styles. If used, it must appear
|
|
first in the list of keywords.</p>
|
|
<p>Its meaning is that all the following parameters will only be modified
|
|
for the specified sub-style. If the sub-style is defined multiple
|
|
times, then an additional numeric argument <em>N</em> must also be specified,
|
|
which is a number from 1 to M where M is the number of times the
|
|
sub-style was listed in the <a class="reference internal" href="pair_hybrid.html"><span class="doc">pair_style hybrid</span></a>
|
|
command. The extra number indicates which instance of the sub-style
|
|
the remaining keywords will be applied to.</p>
|
|
<p>The <em>special</em> and <em>compute/tally</em> keywords can <strong>only</strong> be used in
|
|
conjunction with the <em>pair</em> keyword and they must directly follow it.
|
|
I.e. any other keyword, must appear after <em>pair</em>, <em>special</em>, and
|
|
<em>compute/tally</em>.</p>
|
|
<p>The <em>special</em> keyword overrides the global <a class="reference internal" href="special_bonds.html"><span class="doc">special_bonds</span></a>
|
|
1-2, 1-3, 1-4 exclusion settings (weights) for the sub-style selected
|
|
by the <em>pair</em> keyword.</p>
|
|
<p>Similar to the <a class="reference internal" href="special_bonds.html"><span class="doc">special_bonds</span></a> command, it takes
|
|
4 arguments. The <em>which</em> argument can be <em>lj</em> to change only the
|
|
non-Coulomb weights (e.g. Lennard-Jones or Buckingham), <em>coul</em> to change
|
|
only the Coulombic settings, or <em>lj/coul</em> to change both to the same
|
|
values. The <em>wt1,wt2,wt3</em> values are numeric weights from 0.0 to 1.0
|
|
inclusive, for the 1-2, 1-3, and 1-4 bond topology neighbors, respectively.
|
|
The <em>special</em> keyword can be used multiple times, e.g. to set the <em>lj</em>
|
|
and <em>coul</em> settings to different values.</p>
|
|
<div class="admonition note">
|
|
<p class="admonition-title">Note</p>
|
|
<p>The <em>special</em> keyword is not compatible with pair styles from the
|
|
GPU or the INTEL package and attempting to use it will cause
|
|
an error.</p>
|
|
</div>
|
|
<div class="admonition note">
|
|
<p class="admonition-title">Note</p>
|
|
<p>Weights of exactly 0.0 or 1.0 in the <a class="reference internal" href="special_bonds.html"><span class="doc">special_bonds</span></a>
|
|
command have implications on the neighbor list construction, which
|
|
means that they cannot be overridden by using the <em>special</em> keyword.
|
|
One workaround for this restriction is to use the <a class="reference internal" href="special_bonds.html"><span class="doc">special_bonds</span></a>
|
|
command with weights like 1.0e-10 or 0.999999999 instead of 0.0 or 1.0,
|
|
respectively, which enables to reset each them to any value between 0.0
|
|
and 1.0 inclusively. Otherwise you can set <strong>all</strong> global weights to
|
|
an arbitrary number between 0.0 or 1.0, like 0.5, and then you have
|
|
to override <strong>all</strong> <em>special</em> settings for <strong>all</strong> sub-styles which use
|
|
the 1-2, 1-3, and 1-4 exclusion weights in their force/energy computation.</p>
|
|
</div>
|
|
<p>The <em>compute/tally</em> keyword disables or enables registering <a class="reference internal" href="compute_tally.html"><span class="doc">compute
|
|
*/tally</span></a> computes for the sub-style specified by
|
|
the <em>pair</em> keyword. Use <em>no</em> to disable, or <em>yes</em> to enable.</p>
|
|
<div class="admonition note">
|
|
<p class="admonition-title">Note</p>
|
|
<p>The “pair_modify pair compute/tally” command must be issued
|
|
<strong>before</strong> the corresponding compute style is defined.</p>
|
|
</div>
|
|
<div class="versionadded">
|
|
<p><span class="versionmodified added">Added in version 3Aug2022.</span></p>
|
|
</div>
|
|
<p>The <em>neigh/trim</em> keyword controls whether an explicit cutoff is set for
|
|
each neighbor list request issued by individual pair sub-styles when
|
|
using <a class="reference internal" href="pair_hybrid.html"><span class="doc">pair hybrid/overlay</span></a>. When this keyword is
|
|
set to <em>no</em>, then the cutoff of each pair sub-style neighbor list will
|
|
be set equal to the largest cutoff, even if a shorter cutoff is
|
|
specified for a particular sub-style. If possible the neighbor list
|
|
will be copied directly from another list. When this keyword is set to
|
|
<em>yes</em> then the cutoff of the neighbor list will be explicitly set to the
|
|
value requested by the pair sub-style, and if possible the list will be
|
|
created by trimming neighbors from another list with a longer cutoff,
|
|
otherwise a new neighbor list will be created with the specified cutoff.
|
|
The <em>yes</em> option can be faster when there are multiple pair styles with
|
|
different cutoffs since the number of pair-wise distance checks between
|
|
neighbors is reduced (but the time required to build the neighbor lists
|
|
is increased). The <em>no</em> option could be faster when two or more neighbor
|
|
lists have similar (but not exactly the same) cutoffs.</p>
|
|
<div class="admonition note">
|
|
<p class="admonition-title">Note</p>
|
|
<p>The “pair_modify neigh/trim” command <em>only</em> applies when there are
|
|
multiple pair sub-styles for the same atoms with different cutoffs,
|
|
i.e. when using pair style hybrid/overlay. If you have different
|
|
cutoffs for different pairs for atoms type, the <a class="reference internal" href="neighbor.html"><span class="doc">neighbor style
|
|
multi</span></a> should be used to create optimized neighbor lists.</p>
|
|
</div>
|
|
</section>
|
|
<hr class="docutils" />
|
|
<section id="restrictions">
|
|
<h2>Restrictions<a class="headerlink" href="#restrictions" title="Link to this heading"></a></h2>
|
|
<p>You cannot use <em>shift</em> yes with <em>tail</em> yes, since those are
|
|
conflicting options. You cannot use <em>tail</em> yes with 2d simulations.
|
|
You cannot use <em>special</em> with pair styles from the GPU or
|
|
INTEL package.</p>
|
|
</section>
|
|
<section id="related-commands">
|
|
<h2>Related commands<a class="headerlink" href="#related-commands" title="Link to this heading"></a></h2>
|
|
<p><a class="reference internal" href="pair_style.html"><span class="doc">pair_style</span></a>, <a class="reference internal" href="pair_hybrid.html"><span class="doc">pair_style hybrid</span></a>,
|
|
<a class="reference internal" href="pair_coeff.html"><span class="doc">pair_coeff</span></a>, <a class="reference internal" href="thermo_style.html"><span class="doc">thermo_style</span></a>,
|
|
<a class="reference internal" href="compute_tally.html"><span class="doc">compute */tally</span></a>, <a class="reference internal" href="neighbor.html"><span class="doc">neighbor multi</span></a></p>
|
|
</section>
|
|
<section id="default">
|
|
<h2>Default<a class="headerlink" href="#default" title="Link to this heading"></a></h2>
|
|
<p>The option defaults are mix = geometric, shift = no, table = 12,
|
|
tabinner = sqrt(2.0), tail = no, compute = yes, and neigh/trim yes.</p>
|
|
<p>Note that some pair styles perform mixing, but only a certain style of
|
|
mixing. See the doc pages for individual pair styles for details.</p>
|
|
<hr class="docutils" />
|
|
<p id="wolff1"><strong>(Wolff)</strong> Wolff and Rudd, Comp Phys Comm, 120, 200-32 (1999).</p>
|
|
<p id="sun"><strong>(Sun)</strong> Sun, J Phys Chem B, 102, 7338-7364 (1998).</p>
|
|
</section>
|
|
</section>
|
|
|
|
|
|
</div>
|
|
</div>
|
|
<footer><div class="rst-footer-buttons" role="navigation" aria-label="Footer">
|
|
<a href="pair_coeff.html" class="btn btn-neutral float-left" title="pair_coeff command" accesskey="p" rel="prev"><span class="fa fa-arrow-circle-left" aria-hidden="true"></span> Previous</a>
|
|
<a href="pair_style.html" class="btn btn-neutral float-right" title="pair_style command" accesskey="n" rel="next">Next <span class="fa fa-arrow-circle-right" aria-hidden="true"></span></a>
|
|
</div>
|
|
|
|
<hr/>
|
|
|
|
<div role="contentinfo">
|
|
<p>© Copyright 2003-2025 Sandia Corporation.</p>
|
|
</div>
|
|
|
|
Built with <a href="https://www.sphinx-doc.org/">Sphinx</a> using a
|
|
<a href="https://github.com/readthedocs/sphinx_rtd_theme">theme</a>
|
|
provided by <a href="https://readthedocs.org">Read the Docs</a>.
|
|
|
|
|
|
</footer>
|
|
</div>
|
|
</div>
|
|
</section>
|
|
</div>
|
|
<script>
|
|
jQuery(function () {
|
|
SphinxRtdTheme.Navigation.enable(false);
|
|
});
|
|
</script>
|
|
|
|
</body>
|
|
</html> |