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<div class="section" id="compute-displace-atom-command">
<span id="index-0"></span><h1>compute displace/atom command</h1>
<div class="section" id="syntax">
<h2>Syntax</h2>
<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">displace</span><span class="o">/</span><span class="n">atom</span>
</pre></div>
</div>
<ul class="simple">
<li>ID, group-ID are documented in <a class="reference internal" href="compute.html"><span class="doc">compute</span></a> command</li>
<li>displace/atom = style name of this compute 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">compute</span> <span class="mi">1</span> <span class="nb">all</span> <span class="n">displace</span><span class="o">/</span><span class="n">atom</span>
</pre></div>
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</div>
<div class="section" id="description">
<h2>Description</h2>
<p>Define a computation that calculates the current displacement of each
atom in the group from its original coordinates, including all effects
due to atoms passing thru periodic boundaries.</p>
<p>A vector of four quantites per atom is calculated by this compute.
The first 3 elements of the vector are the dx,dy,dz displacements.
The 4th component is the total displacement, i.e. sqrt(dx*dx + dy*dy +
dz*dz).</p>
<p>The displacement of an atom is from its original position at the time
the compute command was issued. The value of the displacement will be
0.0 for atoms not in the specified compute group.</p>
<div class="admonition note">
<p class="first admonition-title">Note</p>
<p class="last">Initial coordinates are stored in &#8220;unwrapped&#8221; form, by using the
image flags associated with each atom. See the <a class="reference internal" href="dump.html"><span class="doc">dump custom</span></a> command for a discussion of &#8220;unwrapped&#8221; coordinates.
See the Atoms section of the <a class="reference internal" href="read_data.html"><span class="doc">read_data</span></a> command for a
discussion of image flags and how they are set for each atom. You can
reset the image flags (e.g. to 0) before invoking this compute by
using the <a class="reference internal" href="set.html"><span class="doc">set image</span></a> command.</p>
</div>
<div class="admonition note">
<p class="first admonition-title">Note</p>
<p class="last">If you want the quantities calculated by this compute to be
continuous when running from a <a class="reference internal" href="read_restart.html"><span class="doc">restart file</span></a>, then
you should use the same ID for this compute, as in the original run.
This is so that the fix this compute creates to store per-atom
quantities will also have the same ID, and thus be initialized
correctly with time=0 atom coordinates from the restart file.</p>
</div>
<p><strong>Output info:</strong></p>
<p>This compute calculates a per-atom array with 4 columns, which can be
accessed by indices 1-4 by any command that uses per-atom values from
a compute as input. See <a class="reference internal" href="Section_howto.html#howto-15"><span class="std std-ref">Section_howto 15</span></a> for an overview of LAMMPS output
options.</p>
<p>The per-atom array values will be in distance <a class="reference internal" href="units.html"><span class="doc">units</span></a>.</p>
</div>
<div class="section" id="restrictions">
<h2>Restrictions</h2>
<blockquote>
<div>none</div></blockquote>
</div>
<div class="section" id="related-commands">
<h2>Related commands</h2>
<p><a class="reference internal" href="compute_msd.html"><span class="doc">compute msd</span></a>, <a class="reference internal" href="dump.html"><span class="doc">dump custom</span></a>, <a class="reference internal" href="fix_store_state.html"><span class="doc">fix store/state</span></a></p>
<p><strong>Default:</strong> none</p>
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