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<div class="section" id="improper-style-distance-command">
<span id="index-0"></span><h1>improper_style distance command<a class="headerlink" href="#improper-style-distance-command" title="Permalink to this headline">¶</a></h1>
<div class="section" id="syntax">
<h2>Syntax<a class="headerlink" href="#syntax" title="Permalink to this headline">¶</a></h2>
<p>improper_style distance</p>
</div>
<div class="section" id="examples">
<h2>Examples<a class="headerlink" href="#examples" title="Permalink to this headline">¶</a></h2>
<div class="highlight-python"><div class="highlight"><pre>improper_style distance
improper_coeff 1 80.0 100.0
</pre></div>
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<div class="section" id="description">
<h2>Description<a class="headerlink" href="#description" title="Permalink to this headline">¶</a></h2>
<p>The <em>distance</em> improper style uses the potential</p>
<img alt="Eqs/improper_dist-1.jpg" class="align-center" src="Eqs/improper_dist-1.jpg" />
<p>where d is the distance between the central atom and the plane formed
by the other three atoms. If the 4 atoms in an improper quadruplet
(listed in the data file read by the <a class="reference internal" href="read_data.html"><em>read_data</em></a>
command) are ordered I,J,K,L then the I-atom is assumed to be the
central atom.</p>
<img alt="JPG/improper_distance.jpg" class="align-center" src="JPG/improper_distance.jpg" />
<p>Note that defining 4 atoms to interact in this way, does not mean that
bonds necessarily exist between I-J, J-K, or K-L, as they would in a
linear dihedral. Normally, the bonds I-J, I-K, I-L would exist for an
improper to be defined between the 4 atoms.</p>
<p>The following coefficients must be defined for each improper type via
the improper_coeff command as in the example above, or in the data
file or restart files read by the read_data or read_restart commands:</p>
<ul class="simple">
<li>K_2 (energy/distance^2)</li>
<li>K_4 (energy/distance^4)</li>
</ul>
</div>
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<div class="section" id="restrictions">
<h2>Restrictions<a class="headerlink" href="#restrictions" title="Permalink to this headline">¶</a></h2>
<p>This improper style can only be used if LAMMPS was built with the
USER-MISC package. See the <a class="reference internal" href="Section_start.html#start-3"><span>Making LAMMPS</span></a>
section for more info on packages.</p>
</div>
<div class="section" id="related-commands">
<h2>Related commands<a class="headerlink" href="#related-commands" title="Permalink to this headline">¶</a></h2>
<p><a class="reference internal" href="improper_coeff.html"><em>improper_coeff</em></a></p>
<p><strong>Default:</strong> none</p>
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