<spanid="index-0"></span><h1>compute ke/eff command<aclass="headerlink"href="#compute-ke-eff-command"title="Permalink to this headline">¶</a></h1>
<divclass="section"id="syntax">
<h2>Syntax<aclass="headerlink"href="#syntax"title="Permalink to this headline">¶</a></h2>
<divclass="highlight-python"><divclass="highlight"><pre>compute ID group-ID ke/eff
</pre></div>
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<ulclass="simple">
<li>ID, group-ID are documented in <aclass="reference internal"href="compute.html"><em>compute</em></a> command</li>
<li>ke/eff = style name of this compute command</li>
</ul>
</div>
<divclass="section"id="examples">
<h2>Examples<aclass="headerlink"href="#examples"title="Permalink to this headline">¶</a></h2>
<divclass="highlight-python"><divclass="highlight"><pre>compute 1 all ke/eff
</pre></div>
</div>
</div>
<divclass="section"id="description">
<h2>Description<aclass="headerlink"href="#description"title="Permalink to this headline">¶</a></h2>
<p>Define a computation that calculates the kinetic energy of motion of a
group of eFF particles (nuclei and electrons), as modeled with the
<aclass="reference internal"href="pair_eff.html"><em>electronic force field</em></a>.</p>
<p>The kinetic energy for each nucleus is computed as 1/2 m v^2 and the
kinetic energy for each electron is computed as 1/2(me v^2 + 3/4 me
s^2), where m corresponds to the nuclear mass, me to the electron
mass, v to the translational velocity of each particle, and s to the
radial velocity of the electron, respectively.</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
<aclass="reference internal"href="thermo_style.html"><em>thermo_style</em></a> command. For this compute, kinetic
energy is “translational” and “radial” (only for electrons) 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 eFF temperature computation via the <aclass="reference internal"href="compute_temp_eff.html"><em>compute temp_eff</em></a> command, these are the same. But
different computes that calculate temperature can subtract out
different non-thermal components of velocity and/or include other
degrees of freedom.</p>
<p>IMPRORTANT NOTE: The temperature in eFF models should be monitored via
the <aclass="reference internal"href="compute_temp_eff.html"><em>compute temp/eff</em></a> command, which can be
printed with thermodynamic output by using the
<aclass="reference internal"href="thermo_modify.html"><em>thermo_modify</em></a> command, as shown in the following
example:</p>
<divclass="highlight-python"><divclass="highlight"><pre>compute effTemp all temp/eff
<p>This compute calculates a global scalar (the KE). This value can be
used by any command that uses a global scalar value from a compute as
input. See <aclass="reference internal"href="Section_howto.html#howto-15"><span>Section_howto 15</span></a> for an
overview of LAMMPS output options.</p>
<p>The scalar value calculated by this compute is “extensive”. The
scalar value will be in energy <aclass="reference internal"href="units.html"><em>units</em></a>.</p>
</div>
<divclass="section"id="restrictions">
<h2>Restrictions<aclass="headerlink"href="#restrictions"title="Permalink to this headline">¶</a></h2>
<p>This compute is part of the USER-EFF package. It is only enabled if
LAMMPS was built with that package. See the <aclass="reference internal"href="Section_start.html#start-3"><span>Making LAMMPS</span></a> section for more info.</p>
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