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<div class="section" id="fix-nve-noforce-command">
<span id="index-0"></span><h1>fix nve/noforce command</h1>
<div class="section" id="syntax">
<h2>Syntax</h2>
<div class="highlight-default"><div class="highlight"><pre><span></span><span class="n">fix</span> <span class="n">ID</span> <span class="n">group</span><span class="o">-</span><span class="n">ID</span> <span class="n">nve</span>
</pre></div>
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<ul class="simple">
<li>ID, group-ID are documented in <a class="reference internal" href="fix.html"><span class="doc">fix</span></a> command</li>
<li>nve/noforce = style name of this fix 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">fix</span> <span class="mi">3</span> <span class="n">wall</span> <span class="n">nve</span><span class="o">/</span><span class="n">noforce</span>
</pre></div>
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<div class="section" id="description">
<h2>Description</h2>
<p>Perform updates of position, but not velocity for atoms in the group
each timestep. In other words, the force on the atoms is ignored and
their velocity is not updated. The atom velocities are used to update
their positions.</p>
<p>This can be useful for wall atoms, when you set their velocities, and
want the wall to move (or stay stationary) in a prescribed fashion.</p>
<p>This can also be accomplished via the <a class="reference internal" href="fix_setforce.html"><span class="doc">fix setforce</span></a>
command, but with fix nve/noforce, the forces on the wall atoms are
unchanged, and can thus be printed by the <a class="reference internal" href="dump.html"><span class="doc">dump</span></a> command or
queried with an equal-style <a class="reference internal" href="variable.html"><span class="doc">variable</span></a> that uses the
fcm() group function to compute the total force on the group of atoms.</p>
<p><strong>Restart, fix_modify, output, run start/stop, minimize info:</strong></p>
<p>No information about this fix is written to <a class="reference internal" href="restart.html"><span class="doc">binary restart files</span></a>. None of the <a class="reference internal" href="fix_modify.html"><span class="doc">fix_modify</span></a> options
are relevant to this fix. No global or per-atom quantities are stored
by this fix for access by various <a class="reference internal" href="Section_howto.html#howto-15"><span class="std std-ref">output commands</span></a>. No parameter of this fix can
be used with the <em>start/stop</em> keywords of the <a class="reference internal" href="run.html"><span class="doc">run</span></a> command.
This fix is not invoked during <a class="reference internal" href="minimize.html"><span class="doc">energy minimization</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="fix_nve.html"><span class="doc">fix nve</span></a></p>
<p><strong>Default:</strong> none</p>
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