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<title>pair_style awpmd/cut command &mdash; LAMMPS 15 May 2015 version documentation</title>
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<div class="section" id="pair-style-awpmd-cut-command">
<span id="index-0"></span><h1>pair_style awpmd/cut command<a class="headerlink" href="#pair-style-awpmd-cut-command" title="Permalink to this headline">¶</a></h1>
<div class="section" id="syntax">
<h2>Syntax<a class="headerlink" href="#syntax" title="Permalink to this headline">¶</a></h2>
<div class="highlight-python"><div class="highlight"><pre>pair_style awpmd/cut Rc keyword value ...
</pre></div>
</div>
<ul class="simple">
<li>Rc = global cutoff, -1 means cutoff of half the shortest box length</li>
<li>zero or more keyword/value pairs may be appended</li>
<li>keyword = <em>hartree</em> or <em>dproduct</em> or <em>uhf</em> or <em>free</em> or <em>pbc</em> or <em>fix</em> or <em>harm</em> or <em>ermscale</em> or <em>flex_press</em></li>
</ul>
<pre class="literal-block">
<em>hartree</em> value = none
<em>dproduct</em> value = none
<em>uhf</em> value = none
<em>free</em> value = none
<em>pbc</em> value = Plen
Plen = periodic width of electron = -1 or positive value (distance units)
<em>fix</em> value = Flen
Flen = fixed width of electron = -1 or positive value (distance units)
<em>harm</em> value = width
width = harmonic width constraint
<em>ermscale</em> value = factor
factor = scaling between electron mass and width variable mass
<em>flex_press</em> value = none
</pre>
</div>
<div class="section" id="examples">
<h2>Examples<a class="headerlink" href="#examples" title="Permalink to this headline">¶</a></h2>
<div class="highlight-python"><div class="highlight"><pre>pair_style awpmd/cut -1
pair_style awpmd/cut 40.0 uhf free
pair_coeff * *
pair_coeff 2 2 20.0
</pre></div>
</div>
</div>
<div class="section" id="description">
<h2>Description<a class="headerlink" href="#description" title="Permalink to this headline">¶</a></h2>
<p>This pair style contains an implementation of the Antisymmetrized Wave
Packet Molecular Dynamics (AWPMD) method. Need citation here. Need
basic formulas here. Could be links to other documents.</p>
<p>Rc is the cutoff.</p>
<p>The pair_style command allows for several optional keywords
to be specified.</p>
<p>The <em>hartree</em>, <em>dproduct</em>, and <em>uhf</em> keywords specify the form of the
initial trial wave function for the system. If the <em>hartree</em> keyword
is used, then a Hartree multielectron trial wave function is used. If
the <em>dproduct</em> keyword is used, then a trial function which is a
product of two determinants for each spin type is used. If the <em>uhf</em>
keyword is used, then an unrestricted Hartree-Fock trial wave function
is used.</p>
<p>The <em>free</em>, <em>pbc</em>, and <em>fix</em> keywords specify a width constraint on
the electron wavepackets. If the <em>free</em> keyword is specified, then there is no
constraint. If the <em>pbc</em> keyword is used and <em>Plen</em> is specified as
-1, then the maximum width is half the shortest box length. If <em>Plen</em>
is a positive value, then the value is the maximum width. If the
<em>fix</em> keyword is used and <em>Flen</em> is specified as -1, then electrons
have a constant width that is read from the data file. If <em>Flen</em> is a
positive value, then the constant width for all electrons is set to
<em>Flen</em>.</p>
<p>The <em>harm</em> keyword allow oscillations in the width of the
electron wavepackets. More details are needed.</p>
<p>The <em>ermscale</em> keyword specifies a unitless scaling factor
between the electron masses and the width variable mass. More
details needed.</p>
<p>If the <em>flex_press</em> keyword is used, then a contribution from the
electrons is added to the total virial and pressure of the system.</p>
<p>This potential is designed to be used with <a class="reference internal" href="atom_style.html"><em>atom_style wavepacket</em></a> definitions, in order to handle the
description of systems with interacting nuclei and explicit electrons.</p>
<p>The following coefficients must be defined for each pair of atoms
types via the <a class="reference internal" href="pair_coeff.html"><em>pair_coeff</em></a> command as in the examples
above, or in the data file or restart files read by the
<a class="reference internal" href="read_data.html"><em>read_data</em></a> or <a class="reference internal" href="read_restart.html"><em>read_restart</em></a>
commands, or by mixing as described below:</p>
<ul class="simple">
<li>cutoff (distance units)</li>
</ul>
<p>For <em>awpmd/cut</em>, the cutoff coefficient is optional. If it is not
used (as in some of the examples above), the default global value
specified in the pair_style command is used.</p>
<hr class="docutils" />
<p><strong>Mixing, shift, table, tail correction, restart, rRESPA info</strong>:</p>
<p>The <a class="reference internal" href="pair_modify.html"><em>pair_modify</em></a> mix, shift, table, and tail options
are not relevant for this pair style.</p>
<p>This pair style writes its information to <a class="reference internal" href="restart.html"><em>binary restart files</em></a>, so pair_style and pair_coeff commands do not need
to be specified in an input script that reads a restart file.</p>
<p>This pair style can only be used via the <em>pair</em> keyword of the
<a class="reference internal" href="run_style.html"><em>run_style respa</em></a> command. It does not support the
<em>inner</em>, <em>middle</em>, <em>outer</em> keywords.</p>
</div>
<hr class="docutils" />
<div class="section" id="restrictions">
<h2>Restrictions<a class="headerlink" href="#restrictions" title="Permalink to this headline">¶</a></h2>
<blockquote>
<div>none</div></blockquote>
</div>
<div class="section" id="related-commands">
<h2>Related commands<a class="headerlink" href="#related-commands" title="Permalink to this headline">¶</a></h2>
<p><a class="reference internal" href="pair_coeff.html"><em>pair_coeff</em></a></p>
</div>
<div class="section" id="default">
<h2>Default<a class="headerlink" href="#default" title="Permalink to this headline">¶</a></h2>
<p>These are the defaults for the pair_style keywords: <em>hartree</em> for the
initial wavefunction, <em>free</em> for the wavepacket width.</p>
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