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<div class="section" id="fix-shardlow-command">
<span id="index-0"></span><h1>fix shardlow command</h1>
<div class="section" id="syntax">
<h2>Syntax</h2>
<div class="highlight-default"><div class="highlight"><pre><span></span><span class="n">fix</span> <span class="n">ID</span> <span class="n">group</span><span class="o">-</span><span class="n">ID</span> <span class="n">shardlow</span>
</pre></div>
</div>
<ul class="simple">
<li>ID, group-ID are documented in <a class="reference internal" href="fix.html"><span class="doc">fix</span></a> command</li>
<li>shardlow = style name of this fix command</li>
</ul>
</div>
<div class="section" id="examples">
<h2>Examples</h2>
<div class="highlight-default"><div class="highlight"><pre><span></span><span class="n">fix</span> <span class="mi">1</span> <span class="nb">all</span> <span class="n">shardlow</span>
</pre></div>
</div>
</div>
<div class="section" id="description">
<h2>Description</h2>
<p>Specifies that the Shardlow splitting algorithm (SSA) is to be used to
integrate the DPD equations of motion. The SSA splits the integration
into a stochastic and deterministic integration step. The fix
<em>shardlow</em> performs the stochastic integration step and must be used
in conjunction with a deterministic integrator (e.g. <span class="xref doc">fix nve</span> or <span class="xref doc">fix nph</span>). The stochastic
integration of the dissipative and random forces is performed prior to
the deterministic integration of the conservative force. Further
details regarding the method are provided in <a class="reference internal" href="pair_dpd_fdt.html#lisal"><span class="std std-ref">(Lisal)</span></a> and
<a class="reference internal" href="fix_eos_cv.html#larentzos"><span class="std std-ref">(Larentzos)</span></a>.</p>
<p>The fix <em>shardlow</em> must be used with the <a class="reference internal" href="pair_style.html"><span class="doc">pair_style dpd/fdt</span></a> or <a class="reference internal" href="pair_style.html"><span class="doc">pair_style dpd/fdt/energy</span></a> command to properly initialize the
fluctuation-dissipation theorem parameter(s) sigma (and kappa, if
necessary).</p>
<p>Note that numerous variants of DPD can be specified by choosing an
appropriate combination of the integrator and <a class="reference internal" href="pair_style.html"><span class="doc">pair_style dpd/fdt</span></a> command. DPD under isothermal conditions can
be specified by using fix <em>shardlow</em>, fix <em>nve</em> and pair_style
<em>dpd/fdt</em>. DPD under isoenergetic conditions can be specified by
using fix <em>shardlow</em>, fix <em>nve</em> and pair_style <em>dpd/fdt/energy</em>. DPD
under isobaric conditions can be specified by using fix shardlow, fix
<em>nph</em> and pair_style <em>dpd/fdt</em>. DPD under isoenthalpic conditions can
be specified by using fix shardlow, fix <em>nph</em> and pair_style
<em>dpd/fdt/energy</em>. Examples of each DPD variant are provided in the
examples/USER/dpd directory.</p>
</div>
<hr class="docutils" />
<div class="section" id="restrictions">
<h2>Restrictions</h2>
<p>This fix is only available if LAMMPS is built with the USER-DPD
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>
<p>This fix is currently limited to orthogonal simulation cell
geometries.</p>
<p>This fix must be used with an additional fix that specifies time
integration, e.g. <span class="xref doc">fix nve</span> or <a class="reference internal" href="fix_nh.html"><span class="doc">fix nph</span></a>.</p>
<p>The Shardlow splitting algorithm requires the sizes of the sub-domain
lengths to be larger than twice the cutoff+skin. Generally, the
domain decomposition is dependant on the number of processors
requested.</p>
</div>
<div class="section" id="related-commands">
<h2>Related commands</h2>
<p><a class="reference internal" href="pair_dpd_fdt.html"><span class="doc">pair_style dpd/fdt</span></a>, <a class="reference internal" href="fix_eos_cv.html"><span class="doc">fix eos/cv</span></a></p>
<p><strong>Default:</strong> none</p>
<hr class="docutils" />
<p id="lisal"><strong>(Lisal)</strong> M. Lisal, J.K. Brennan, J. Bonet Avalos, &#8220;Dissipative
particle dynamics as isothermal, isobaric, isoenergetic, and
isoenthalpic conditions using Shardlow-like splitting algorithms.&#8221;,
J. Chem. Phys., 135, 204105 (2011).</p>
<p id="larentzos"><strong>(Larentzos)</strong> J.P. Larentzos, J.K. Brennan, J.D. Moore, M. Lisal and
W.D. Mattson, &#8220;Parallel Implementation of Isothermal and Isoenergetic
Dissipative Particle Dynamics Using Shardlow-Like Splitting
Algorithms&#8221;, Comput. Phys. Commun., 185, 1987-1998 (2014).</p>
<p id="id1"><strong>(Larentzos)</strong> J.P. Larentzos, J.K. Brennan, J.D. Moore, and
W.D. Mattson, &#8220;LAMMPS Implementation of Constant Energy Dissipative
Particle Dynamics (DPD-E)&#8221;, ARL-TR-6863, U.S. Army Research
Laboratory, Aberdeen Proving Ground, MD (2014).</p>
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