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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 sdk command
</H3>
<P><B>Syntax:</B>
</P>
<PRE>angle_style sdk
</PRE>
<PRE>angle_style sdk/omp
</PRE>
<P><B>Examples:</B>
</P>
<PRE>angle_style sdk
angle_coeff 1 300.0 107.0
</PRE>
<P><B>Description:</B>
</P>
<P>The <I>sdk</I> angle style is a combination of the harmonic angle potential,
</P>
<CENTER><IMG SRC = "Eqs/angle_harmonic.jpg">
</CENTER>
<P>where theta0 is the equilibrium value of the angle and K a prefactor,
with the <I>repulsive</I> part of the non-bonded <I>lj/sdk</I> pair style
between the atoms 1 and 3. This angle potential is intended for
coarse grained MD simulations with the CMM parametrization using the
<A HREF = "pair_sdk.html">pair_style lj/sdk</A>. Relative to the pair_style
<I>lj/sdk</I>, however, the energy is shifted by <I>epsilon</I>, to avoid sudden
jumps. 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:
</P>
<UL><LI>K (energy/radian^2)
<LI>theta0 (degrees)
</UL>
<P>Theta0 is specified in degrees, but LAMMPS converts it to radians
internally; hence the units of K are in energy/radian^2.
The also required <I>lj/sdk</I> parameters will be extracted automatically
from the pair_style.
</P>
<P><B>Restrictions:</B>
</P>
<P>This angle style can only be used if LAMMPS was built with the
USER-CG-CMM package. See the <A HREF = "Section_start.html#start_3">Making
LAMMPS</A> section for more info on packages.
</P>
<P><B>Related commands:</B>
</P>
<P><A HREF = "angle_coeff.html">angle_coeff</A>, <A HREF = "angle_harmonic.html">angle_style
harmonic</A>, <A HREF = "pair_sdk.html">pair_style lj/sdk</A>,
<A HREF = "pair_sdk.html">pair_style lj/sdk/coul/long</A>
</P>
<P><B>Default:</B> none
</P>
</HTML>
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