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<li class="toctree-l1"><a class="reference internal" href="Section_intro.html">1. Introduction</a></li>
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<li class="toctree-l1"><a class="reference internal" href="Section_accelerate.html">5. Accelerating LAMMPS performance</a></li>
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<li>compute event/displace command</li>
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<div class="section" id="compute-event-displace-command">
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<span id="index-0"></span><h1>compute event/displace command</h1>
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<div class="section" id="syntax">
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<h2>Syntax</h2>
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<div class="highlight-default"><div class="highlight"><pre><span></span><span class="n">compute</span> <span class="n">ID</span> <span class="n">group</span><span class="o">-</span><span class="n">ID</span> <span class="n">event</span><span class="o">/</span><span class="n">displace</span> <span class="n">threshold</span>
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</pre></div>
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</div>
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<ul class="simple">
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<li>ID, group-ID are documented in <a class="reference internal" href="compute.html"><span class="doc">compute</span></a> command</li>
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<li>event/displace = style name of this compute command</li>
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<li>threshold = minimum distance anyparticle must move to trigger an event (distance units)</li>
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</ul>
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</div>
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<div class="section" id="examples">
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<h2>Examples</h2>
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<div class="highlight-default"><div class="highlight"><pre><span></span><span class="n">compute</span> <span class="mi">1</span> <span class="nb">all</span> <span class="n">event</span><span class="o">/</span><span class="n">displace</span> <span class="mf">0.5</span>
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</pre></div>
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</div>
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</div>
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<div class="section" id="description">
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<h2>Description</h2>
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<p>Define a computation that flags an “event” if any particle in the
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group has moved a distance greater than the specified threshold
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distance when compared to a previously stored reference state
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(i.e. the previous event). This compute is typically used in
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conjunction with the <a class="reference internal" href="prd.html"><span class="doc">prd</span></a> and <a class="reference internal" href="tad.html"><span class="doc">tad</span></a> commands,
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to detect if a transition
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to a new minimum energy basin has occurred.</p>
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<p>This value calculated by the compute is equal to 0 if no particle has
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moved far enough, and equal to 1 if one or more particles have moved
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further than the threshold distance.</p>
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<div class="admonition note">
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<p class="first admonition-title">Note</p>
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<p class="last">If the system is undergoing significant center-of-mass motion,
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due to thermal motion, an external force, or an initial net momentum,
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then this compute will not be able to distinguish that motion from
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local atom displacements and may generate “false postives.”</p>
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</div>
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<p><strong>Output info:</strong></p>
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<p>This compute calculates a global scalar (the flag). This value can be
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used by any command that uses a global scalar value from a compute as
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input. See <a class="reference internal" href="Section_howto.html#howto-15"><span class="std std-ref">Section_howto 15</span></a> for an
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overview of LAMMPS output options.</p>
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<p>The scalar value calculated by this compute is “intensive”. The
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scalar value will be a 0 or 1 as explained above.</p>
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</div>
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<div class="section" id="restrictions">
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<h2>Restrictions</h2>
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<p>This command can only be used if LAMMPS was built with the REPLICA
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package. See the <a class="reference internal" href="Section_start.html#start-3"><span class="std std-ref">Making LAMMPS</span></a> section
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for more info on packages.</p>
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</div>
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<div class="section" id="related-commands">
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<h2>Related commands</h2>
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<p><a class="reference internal" href="prd.html"><span class="doc">prd</span></a>, <a class="reference internal" href="tad.html"><span class="doc">tad</span></a></p>
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<p><strong>Default:</strong> none</p>
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