lammps/doc/html/angle_style.html

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<div class="section" id="angle-style-command">
<span id="index-0"></span><h1>angle_style command</h1>
<div class="section" id="syntax">
<h2>Syntax</h2>
<div class="highlight-default"><div class="highlight"><pre><span></span><span class="n">angle_style</span> <span class="n">style</span>
</pre></div>
</div>
<ul class="simple">
<li>style = <em>none</em> or <em>hybrid</em> or <em>charmm</em> or <em>class2</em> or <em>cosine</em> or <em>cosine/squared</em> or <em>harmonic</em></li>
</ul>
</div>
<div class="section" id="examples">
<h2>Examples</h2>
<div class="highlight-default"><div class="highlight"><pre><span></span><span class="n">angle_style</span> <span class="n">harmonic</span>
<span class="n">angle_style</span> <span class="n">charmm</span>
<span class="n">angle_style</span> <span class="n">hybrid</span> <span class="n">harmonic</span> <span class="n">cosine</span>
</pre></div>
</div>
</div>
<div class="section" id="description">
<h2>Description</h2>
<p>Set the formula(s) LAMMPS uses to compute angle interactions between
triplets of atoms, which remain in force for the duration of the
simulation. The list of angle triplets is read in by a
<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> command
from a data or restart file.</p>
<p>Hybrid models where angles are computed using different angle
potentials can be setup using the <em>hybrid</em> angle style.</p>
<p>The coefficients associated with a angle style can be specified in a
data or restart file or via the <a class="reference internal" href="angle_coeff.html"><span class="doc">angle_coeff</span></a> command.</p>
<p>All angle potentials store their coefficient data in binary restart
files which means angle_style and <a class="reference internal" href="angle_coeff.html"><span class="doc">angle_coeff</span></a>
commands do not need to be re-specified in an input script that
restarts a simulation. See the <a class="reference internal" href="read_restart.html"><span class="doc">read_restart</span></a>
command for details on how to do this. The one exception is that
angle_style <em>hybrid</em> only stores the list of sub-styles in the restart
file; angle coefficients need to be re-specified.</p>
<div class="admonition note">
<p class="first admonition-title">Note</p>
<p class="last">When both an angle and pair style is defined, the
<a class="reference internal" href="special_bonds.html"><span class="doc">special_bonds</span></a> command often needs to be used to
turn off (or weight) the pairwise interaction that would otherwise
exist between 3 bonded atoms.</p>
</div>
<p>In the formulas listed for each angle style, <em>theta</em> is the angle
between the 3 atoms in the angle.</p>
<hr class="docutils" />
<p>Here is an alphabetic list of angle styles defined in LAMMPS. Click on
the style to display the formula it computes and coefficients
specified by the associated <a class="reference internal" href="angle_coeff.html"><span class="doc">angle_coeff</span></a> command.</p>
<p>Note that there are also additional angle styles submitted by users
which are included in the LAMMPS distribution. The list of these with
links to the individual styles are given in the angle section of <a class="reference internal" href="Section_commands.html#cmd-5"><span class="std std-ref">this page</span></a>.</p>
<ul class="simple">
<li><a class="reference internal" href="angle_none.html"><span class="doc">angle_style none</span></a> - turn off angle interactions</li>
<li><a class="reference internal" href="angle_zero.html"><span class="doc">angle_style zero</span></a> - topology but no interactions</li>
<li><a class="reference internal" href="angle_hybrid.html"><span class="doc">angle_style hybrid</span></a> - define multiple styles of angle interactions</li>
<li><a class="reference internal" href="angle_charmm.html"><span class="doc">angle_style charmm</span></a> - CHARMM angle</li>
<li><a class="reference internal" href="angle_class2.html"><span class="doc">angle_style class2</span></a> - COMPASS (class 2) angle</li>
<li><a class="reference internal" href="angle_cosine.html"><span class="doc">angle_style cosine</span></a> - cosine angle potential</li>
<li><a class="reference internal" href="angle_cosine_delta.html"><span class="doc">angle_style cosine/delta</span></a> - difference of cosines angle potential</li>
<li><a class="reference internal" href="angle_cosine_periodic.html"><span class="doc">angle_style cosine/periodic</span></a> - DREIDING angle</li>
<li><a class="reference internal" href="angle_cosine_squared.html"><span class="doc">angle_style cosine/squared</span></a> - cosine squared angle potential</li>
<li><a class="reference internal" href="angle_harmonic.html"><span class="doc">angle_style harmonic</span></a> - harmonic angle</li>
<li><a class="reference internal" href="angle_table.html"><span class="doc">angle_style table</span></a> - tabulated by angle</li>
</ul>
</div>
<hr class="docutils" />
<div class="section" id="restrictions">
<h2>Restrictions</h2>
<p>Angle styles can only be set for atom_styles that allow angles to be
defined.</p>
<p>Most angle styles are part of the MOLECULE package. They are only
enabled if LAMMPS was built with that 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.
The doc pages for individual bond potentials tell if it is part of a
package.</p>
</div>
<div class="section" id="related-commands">
<h2>Related commands</h2>
<p><a class="reference internal" href="angle_coeff.html"><span class="doc">angle_coeff</span></a></p>
</div>
<div class="section" id="default">
<h2>Default</h2>
<div class="highlight-default"><div class="highlight"><pre><span></span><span class="n">angle_style</span> <span class="n">none</span>
</pre></div>
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