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<div class="section" id="improper-style-distance-command">
<span id="index-0"></span><h1>improper_style distance command</h1>
<div class="section" id="syntax">
<h2>Syntax</h2>
<p>improper_style distance</p>
</div>
<div class="section" id="examples">
<h2>Examples</h2>
<div class="highlight-default"><div class="highlight"><pre><span></span><span class="n">improper_style</span> <span class="n">distance</span>
<span class="n">improper_coeff</span> <span class="mi">1</span> <span class="mf">80.0</span> <span class="mf">100.0</span>
</pre></div>
</div>
</div>
<div class="section" id="description">
<h2>Description</h2>
<p>The <em>distance</em> improper style uses the potential</p>
<img alt="_images/improper_dist-1.jpg" class="align-center" src="_images/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"><span class="doc">read_data</span></a>
command) are ordered I,J,K,L then the I-atom is assumed to be the
central atom.</p>
<img alt="_images/improper_distance.jpg" class="align-center" src="_images/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>
<hr class="docutils" />
<div class="section" id="restrictions">
<h2>Restrictions</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 class="std std-ref">Making LAMMPS</span></a>
section for more info on packages.</p>
</div>
<div class="section" id="related-commands">
<h2>Related commands</h2>
<p><a class="reference internal" href="improper_coeff.html"><span class="doc">improper_coeff</span></a></p>
<p><strong>Default:</strong> none</p>
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