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<div class="section" id="compute-com-command">
<span id="index-0"></span><h1>compute com 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">com</span>
</pre></div>
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<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>com = 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">com</span>
</pre></div>
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<div class="section" id="description">
<h2>Description</h2>
<p>Define a computation that calculates the center-of-mass of the group
of atoms, including all effects due to atoms passing thru periodic
boundaries.</p>
<p>A vector of three quantites is calculated by this compute, which
are the x,y,z coordinates of the center of mass.</p>
<div class="admonition note">
<p class="first admonition-title">Note</p>
<p class="last">The coordinates of an atom contribute to the center-of-mass 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>
<p><strong>Output info:</strong></p>
<p>This compute calculates a global vector of length 3, which can be
accessed by indices 1-3 by any command that uses global vector values
from a compute as input. See <a class="reference internal" href="Section_howto.html#howto-15"><span class="std std-ref">this section</span></a> for an overview of LAMMPS output
options.</p>
<p>The vector values are &#8220;intensive&#8221;. The vector 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_com_chunk.html"><span class="doc">compute com/chunk</span></a></p>
<p><strong>Default:</strong> none</p>
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