lammps/doc/angle_cosine_squared.html

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<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>
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<H3>angle_style cosine/squared command
</H3>
<P><B>Syntax:</B>
</P>
<PRE>angle_style cosine/squared
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<P><B>Examples:</B>
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<PRE>angle_style cosine/squared
angle_coeff 2*4 75.0 100.0
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<P><B>Description:</B>
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<P>The <I>cosine/squared</I> angle style uses the potential
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<CENTER><IMG SRC = "Eqs/angle_cosine_squared.jpg">
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<P>where theta0 is the equilibrium value of the angle, and K is a
prefactor. Note that the usual 1/2 factor is included in K.
</P>
<P>The following coefficients must be defined for each angle type via the
<A HREF = "angle_coeff.html">angle_coeff</A> command as in the example above, or in
the data file or restart files read by the <A HREF = "read_data.html">read_data</A>
or <A HREF = "read_restart.html">read_restart</A> commands:
</P>
<UL><LI>K (energy)
<LI>theta0 (degrees)
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<P>Theta0 is specified in degrees, but LAMMPS converts it to radians
internally.
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<P><B>Restrictions:</B>
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<P>This angle style can only be used if LAMMPS was built with the
MOLECULAR package (which it is by default). See the <A HREF = "Section_start.html#start_3">Making
LAMMPS</A> section for more info on packages.
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<P><B>Related commands:</B>
</P>
<P><A HREF = "angle_coeff.html">angle_coeff</A>
</P>
<P><B>Default:</B> none
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