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<div class="section" id="compute-ke-command">
<span id="index-0"></span><h1>compute ke 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">ke</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>ke = 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">ke</span>
</pre></div>
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</div>
<div class="section" id="description">
<h2>Description</h2>
<p>Define a computation that calculates the translational kinetic energy
of a group of particles.</p>
<p>The kinetic energy of each particle is computed as 1/2 m v^2, where m
and v are the mass and velocity of the particle.</p>
<p>There is a subtle difference between the quantity calculated by this
compute and the kinetic energy calculated by the <em>ke</em> or <em>etotal</em>
keyword used in thermodynamic output, as specified by the
<a class="reference internal" href="thermo_style.html"><span class="doc">thermo_style</span></a> command. For this compute, kinetic
energy is &#8220;translational&#8221; kinetic energy, calculated by the simple
formula above. For thermodynamic output, the <em>ke</em> keyword infers
kinetic energy from the temperature of the system with 1/2 Kb T of
energy for each degree of freedom. For the default temperature
computation via the <a class="reference internal" href="compute_temp.html"><span class="doc">compute temp</span></a> command, these
are the same. But different computes that calculate temperature can
subtract out different non-thermal components of velocity and/or
include different degrees of freedom (translational, rotational, etc).</p>
<p><strong>Output info:</strong></p>
<p>This compute calculates a global scalar (the summed KE). This value
can be used by any command that uses a global scalar value 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 scalar value calculated by this compute is &#8220;extensive&#8221;. The
scalar value will be in energy <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_erotate_sphere.html"><span class="doc">compute erotate/sphere</span></a></p>
<p><strong>Default:</strong> none</p>
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