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<div class="section" id="pair-style-born-coul-long-cs-command">
<span id="index-0"></span><h1>pair_style born/coul/long/cs command</h1>
</div>
<div class="section" id="pair-style-buck-coul-long-cs-command">
<h1>pair_style buck/coul/long/cs command</h1>
<div class="section" id="syntax">
<h2>Syntax</h2>
<div class="highlight-default"><div class="highlight"><pre><span></span><span class="n">pair_style</span> <span class="n">style</span> <span class="n">args</span>
</pre></div>
</div>
<ul class="simple">
<li>style = <em>born/coul/long/cs</em> or <em>buck/coul/long/cs</em></li>
<li>args = list of arguments for a particular style</li>
</ul>
<pre class="literal-block">
<em>born/coul/long/cs</em> args = cutoff (cutoff2)
cutoff = global cutoff for non-Coulombic (and Coulombic if only 1 arg) (distance units)
cutoff2 = global cutoff for Coulombic (optional) (distance units)
<em>buck/coul/long/cs</em> args = cutoff (cutoff2)
cutoff = global cutoff for Buckingham (and Coulombic if only 1 arg) (distance units)
cutoff2 = global cutoff for Coulombic (optional) (distance units)
</pre>
</div>
<div class="section" id="examples">
<h2>Examples</h2>
<div class="highlight-default"><div class="highlight"><pre><span></span><span class="n">pair_style</span> <span class="n">born</span><span class="o">/</span><span class="n">coul</span><span class="o">/</span><span class="n">long</span><span class="o">/</span><span class="n">cs</span> <span class="mf">10.0</span> <span class="mf">8.0</span>
<span class="n">pair_coeff</span> <span class="mi">1</span> <span class="mi">1</span> <span class="mf">6.08</span> <span class="mf">0.317</span> <span class="mf">2.340</span> <span class="mf">24.18</span> <span class="mf">11.51</span>
</pre></div>
</div>
<div class="highlight-default"><div class="highlight"><pre><span></span><span class="n">pair_style</span> <span class="n">buck</span><span class="o">/</span><span class="n">coul</span><span class="o">/</span><span class="n">long</span><span class="o">/</span><span class="n">cs</span> <span class="mf">10.0</span>
<span class="n">pair_style</span> <span class="n">buck</span><span class="o">/</span><span class="n">coul</span><span class="o">/</span><span class="n">long</span><span class="o">/</span><span class="n">cs</span> <span class="mf">10.0</span> <span class="mf">8.0</span>
<span class="n">pair_coeff</span> <span class="o">*</span> <span class="o">*</span> <span class="mf">100.0</span> <span class="mf">1.5</span> <span class="mf">200.0</span>
<span class="n">pair_coeff</span> <span class="mi">1</span> <span class="mi">1</span> <span class="mf">100.0</span> <span class="mf">1.5</span> <span class="mf">200.0</span> <span class="mf">9.0</span>
</pre></div>
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</div>
<div class="section" id="description">
<h2>Description</h2>
<p>These pair styles are designed to be used with the adiabatic
core/shell model of <a class="reference internal" href="#mitchellfinchham"><span class="std std-ref">(Mitchell and Finchham)</span></a>. See
<a class="reference internal" href="Section_howto.html#howto-25"><span class="std std-ref">Section_howto 25</span></a> of the manual for an
overview of the model as implemented in LAMMPS.</p>
<p>These pair styles are identical to the <a class="reference internal" href="pair_born.html"><span class="doc">pair_style born/coul/long</span></a> and <a class="reference internal" href="pair_buck.html"><span class="doc">pair_style buck/coul/long</span></a> styles, except they correctly treat the
special case where the distance between two charged core and shell
atoms in the same core/shell pair approach r = 0.0. This needs
special treatment when a long-range solver for Coulombic interactions
is also used, i.e. via the <a class="reference internal" href="kspace_style.html"><span class="doc">kspace_style</span></a> command.</p>
<p>More specifically, the short-range Coulomb interaction between a core
and its shell should be turned off using the
<a class="reference internal" href="special_bonds.html"><span class="doc">special_bonds</span></a> command by setting the 1-2 weight
to 0.0, which works because the core and shell atoms are bonded to
each other. This induces a long-range correction approximation which
fails at small distances (~&lt; 10e-8). Therefore, the Coulomb term which
is used to calculate the correction factor is extended by a minimal
distance (r_min = 1.0-6) when the interaction between a core/shell
pair is treated, as follows</p>
<img alt="_images/pair_cs.jpg" class="align-center" src="_images/pair_cs.jpg" />
<p>where C is an energy-conversion constant, Qi and Qj are the charges on
the core and shell, epsilon is the dielectric constant and r_min is the
minimal distance.</p>
</div>
<div class="section" id="restrictions">
<h2>Restrictions</h2>
<p>These pair styles are part of the CORESHELL package. They are only
enabled if LAMMPS was built with that package. See the <a class="reference internal" href="Section_start.html#start-3"><span class="std std-ref">Making LAMMPS</span></a> section for more info.</p>
</div>
<div class="section" id="related-commands">
<h2>Related commands</h2>
<p><a class="reference internal" href="pair_coeff.html"><span class="doc">pair_coeff</span></a>, <a class="reference internal" href="pair_born.html"><span class="doc">pair_style born</span></a>,
<a class="reference internal" href="pair_buck.html"><span class="doc">pair_style buck</span></a></p>
<p><strong>Default:</strong> none</p>
<hr class="docutils" />
<p id="mitchellfinchham"><strong>(Mitchell and Finchham)</strong> Mitchell, Finchham, J Phys Condensed Matter,
5, 1031-1038 (1993).</p>
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