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<li class="toctree-l2"><a class="reference internal" href="dihedral_charmm.html">dihedral_style charmm command</a></li>
<li class="toctree-l2"><a class="reference internal" href="dihedral_charmm.html#dihedral-style-charmm-intel-command">dihedral_style charmm/intel command</a></li>
<li class="toctree-l2"><a class="reference internal" href="dihedral_charmm.html#dihedral-style-charmm-kk-command">dihedral_style charmm/kk command</a></li>
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<li class="toctree-l2"><a class="reference internal" href="dihedral_helix.html">dihedral_style helix command</a></li>
<li class="toctree-l2"><a class="reference internal" href="dihedral_helix.html#dihedral-style-helix-omp-command">dihedral_style helix/omp command</a></li>
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<li class="toctree-l2"><a class="reference internal" href="dihedral_nharmonic.html">dihedral_style nharmonic command</a></li>
<li class="toctree-l2"><a class="reference internal" href="dihedral_nharmonic.html#dihedral-style-nharmonic-omp-command">dihedral_style nharmonic/omp command</a></li>
<li class="toctree-l2"><a class="reference internal" href="dihedral_none.html">dihedral_style none command</a></li>
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<li class="toctree-l2"><a class="reference internal" href="dihedral_opls.html#dihedral-style-opls-kk-command">dihedral_style opls/kk command</a></li>
<li class="toctree-l2"><a class="reference internal" href="dihedral_opls.html#dihedral-style-opls-omp-command">dihedral_style opls/omp command</a></li>
<li class="toctree-l2 current"><a class="current reference internal" href="#">dihedral_style quadratic command</a></li>
<li class="toctree-l2"><a class="reference internal" href="#dihedral-style-quadratic-omp-command">dihedral_style quadratic/omp command</a><ul>
<li class="toctree-l3"><a class="reference internal" href="#syntax">Syntax</a></li>
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<li class="toctree-l2"><a class="reference internal" href="dihedral_charmm.html#dihedral-style-charmm-kk-command">dihedral_style charmm/kk command</a></li>
<li class="toctree-l2"><a class="reference internal" href="dihedral_charmm.html#dihedral-style-charmm-omp-command">dihedral_style charmm/omp command</a></li>
<li class="toctree-l2"><a class="reference internal" href="dihedral_class2.html">dihedral_style class2 command</a></li>
<li class="toctree-l2"><a class="reference internal" href="dihedral_class2.html#dihedral-style-class2-omp-command">dihedral_style class2/omp command</a></li>
<li class="toctree-l2"><a class="reference internal" href="dihedral_cosine_shift_exp.html">dihedral_style cosine/shift/exp command</a></li>
<li class="toctree-l2"><a class="reference internal" href="dihedral_cosine_shift_exp.html#dihedral-style-cosine-shift-exp-omp-command">dihedral_style cosine/shift/exp/omp command</a></li>
<li class="toctree-l2"><a class="reference internal" href="dihedral_fourier.html">dihedral_style fourier command</a></li>
<li class="toctree-l2"><a class="reference internal" href="dihedral_fourier.html#dihedral-style-fourier-omp-command">dihedral_style fourier/omp command</a></li>
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<li class="toctree-l2"><a class="reference internal" href="dihedral_helix.html">dihedral_style helix command</a></li>
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<li class="toctree-l2"><a class="reference internal" href="dihedral_multi_harmonic.html">dihedral_style multi/harmonic command</a></li>
<li class="toctree-l2"><a class="reference internal" href="dihedral_multi_harmonic.html#dihedral-style-multi-harmonic-omp-command">dihedral_style multi/harmonic/omp command</a></li>
<li class="toctree-l2"><a class="reference internal" href="dihedral_nharmonic.html">dihedral_style nharmonic command</a></li>
<li class="toctree-l2"><a class="reference internal" href="dihedral_nharmonic.html#dihedral-style-nharmonic-omp-command">dihedral_style nharmonic/omp command</a></li>
<li class="toctree-l2"><a class="reference internal" href="dihedral_none.html">dihedral_style none command</a></li>
<li class="toctree-l2"><a class="reference internal" href="dihedral_opls.html">dihedral_style opls command</a></li>
<li class="toctree-l2"><a class="reference internal" href="dihedral_opls.html#dihedral-style-opls-intel-command">dihedral_style opls/intel command</a></li>
<li class="toctree-l2"><a class="reference internal" href="dihedral_opls.html#dihedral-style-opls-kk-command">dihedral_style opls/kk command</a></li>
<li class="toctree-l2"><a class="reference internal" href="dihedral_opls.html#dihedral-style-opls-omp-command">dihedral_style opls/omp command</a></li>
<li class="toctree-l2 current"><a class="current reference internal" href="#">dihedral_style quadratic command</a></li>
<li class="toctree-l2"><a class="reference internal" href="#dihedral-style-quadratic-omp-command">dihedral_style quadratic/omp command</a><ul>
<li class="toctree-l3"><a class="reference internal" href="#syntax">Syntax</a></li>
<li class="toctree-l3"><a class="reference internal" href="#examples">Examples</a></li>
<li class="toctree-l3"><a class="reference internal" href="#description">Description</a></li>
<li class="toctree-l3"><a class="reference internal" href="#restrictions">Restrictions</a></li>
<li class="toctree-l3"><a class="reference internal" href="#related-commands">Related commands</a></li>
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<div class="section" id="dihedral-style-quadratic-command">
<span id="index-0"></span><h1>dihedral_style quadratic command</h1>
</div>
<div class="section" id="dihedral-style-quadratic-omp-command">
<h1>dihedral_style quadratic/omp command</h1>
<div class="section" id="syntax">
<h2>Syntax</h2>
<pre class="literal-block">
dihedral_style quadratic
</pre>
</div>
<div class="section" id="examples">
<h2>Examples</h2>
<pre class="literal-block">
dihedral_style quadratic
dihedral_coeff 100.0 80.0
</pre>
</div>
<div class="section" id="description">
<h2>Description</h2>
<p>The <em>quadratic</em> dihedral style uses the potential:</p>
<img alt="_images/dihedral_quadratic.jpg" class="align-center" src="_images/dihedral_quadratic.jpg" />
<p>This dihedral potential can be used to keep a dihedral in a predefined
value (cis=zero, right-hand convention is used).</p>
<p>The following coefficients must be defined for each dihedral type via
the <a class="reference internal" href="dihedral_coeff.html"><span class="doc">dihedral_coeff</span></a> command as in the example
above, or in the data file or restart files read by the
<a class="reference internal" href="read_data.html"><span class="doc">read_data</span></a> or <a class="reference internal" href="read_restart.html"><span class="doc">read_restart</span></a>
commands:</p>
<ul class="simple">
<li>K (energy/radian^2)</li>
<li>phi0 (degrees)</li>
</ul>
<hr class="docutils" />
<p>Styles with a <em>gpu</em>, <em>intel</em>, <em>kk</em>, <em>omp</em>, or <em>opt</em> suffix are
functionally the same as the corresponding style without the suffix.
They have been optimized to run faster, depending on your available
hardware, as discussed in <a class="reference internal" href="Section_accelerate.html"><span class="doc">Section 5</span></a>
of the manual. The accelerated styles take the same arguments and
should produce the same results, except for round-off and precision
issues.</p>
<p>These accelerated styles are part of the GPU, USER-INTEL, KOKKOS,
USER-OMP and OPT packages, respectively. They are only enabled if
LAMMPS was built with those packages. 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.</p>
<p>You can specify the accelerated styles explicitly in your input script
by including their suffix, or you can use the <a class="reference internal" href="Section_start.html#start-7"><span class="std std-ref">-suffix command-line switch</span></a> when you invoke LAMMPS, or you can
use the <a class="reference internal" href="suffix.html"><span class="doc">suffix</span></a> command in your input script.</p>
<p>See <a class="reference internal" href="Section_accelerate.html"><span class="doc">Section 5</span></a> of the manual for
more instructions on how to use the accelerated styles effectively.</p>
</div>
<hr class="docutils" />
<div class="section" id="restrictions">
<h2>Restrictions</h2>
<p>This angle 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="dihedral_coeff.html"><span class="doc">dihedral_coeff</span></a></p>
<p><strong>Default:</strong> none</p>
</div>
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