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<HTML>
<CENTER><A HREF = "http://lammps.sandia.gov">LAMMPS WWW Site</A> - <A HREF = "Manual.html">LAMMPS Documentation</A> - <A HREF = "Section_commands.html#comm">LAMMPS Commands</A>
</CENTER>
<HR>
<H3>angle_style command
</H3>
<P><B>Syntax:</B>
</P>
<PRE>angle_style style
</PRE>
<UL><LI>style = <I>none</I> or <I>hybrid</I> or <I>charmm</I> or <I>class2</I> or <I>cosine</I> or <I>cosine/squared</I> or <I>harmonic</I>
</UL>
<P><B>Examples:</B>
</P>
<PRE>angle_style harmonic
angle_style charmm
angle_style hybrid harmonic cosine
</PRE>
<P><B>Description:</B>
</P>
<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 HREF = "read_data.html">read_data</A> or <A HREF = "read_restart.html">read_restart</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 <I>hybrid</I> angle style.
</P>
<P>The coefficients associated with a angle style can be specified in a
data or restart file or via the <A HREF = "angle_coeff.html">angle_coeff</A> command.
</P>
<P>In the formulas listed for each angle style, <I>theta</I> is the angle
between the 3 atoms in the angle.
</P>
<P>Note that when both an angle and pair style is defined, the
<A HREF = "special_bond.html">special_bond</A> command often needs to be used to
turn off (or weight) the pairwise interactions that would otherwise
exist between the 3 bonded atoms.
</P>
<HR>
<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 HREF = "angle_coeff.html">angle_coeff</A> command:
</P>
<UL><LI><A HREF = "angle_none.html">angle_style none</A> - turn off angle interactions
<LI><A HREF = "angle_hybrid.html">angle_style hybrid</A> - define multiple styles of angle interactions
</UL>
<UL><LI><A HREF = "angle_charmm.html">angle_style charmm</A> - CHARMM angle
<LI><A HREF = "angle_class2.html">angle_style class2</A> - COMPASS (class 2) angle
<LI><A HREF = "angle_cosine.html">angle_style cosine</A> - cosine angle potential
<LI><A HREF = "angle_cosine_squared.html">angle_style cosine/squared</A> - cosine squared angle potential
<LI><A HREF = "angle_harmonic.html">angle_style harmonic</A> - harmonic angle
</UL>
<HR>
<P><B>Restrictions:</B>
</P>
<P>Angle styles can only be set for atom_styles that allow angles to be
defined.
</P>
<P>Angle styles are part of the "molecular" package or other packages as
noted in their documentation. They are only enabled if LAMMPS was
built with that package. See the <A HREF = "Section_start.html#2_2">Making
LAMMPS</A> section for more info.
</P>
<P><B>Related commands:</B>
</P>
<P><A HREF = "angle_coeff.html">angle_coeff</A>
</P>
<P><B>Default:</B>
</P>
<PRE>angle_style none
</PRE>
</HTML>
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