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angle_hybrid.html
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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 hybrid command
</H3>
<P><B>Syntax:</B>
</P>
<PRE>angle_style hybrid style1 style2 ...
</PRE>
<UL><LI>style1,style2 = list of one or more angle styles
</UL>
<P><B>Examples:</B>
</P>
<PRE>angle_style hybrid harmonic cosine
angle_coeff 1 harmonic 80.0 30.0
angle_coeff 2* cosine 50.0
</PRE>
<P><B>Description:</B>
</P>
<P>The <I>hybrid</I> style enables the use of multiple angle styles in one
simulation. An angle style is assigned to each angle type. For
example, angles in a polymer flow (of angle type 1) could be computed
with a <I>harmonic</I> potential and angles in the wall boundary (of angle
type 2) could be computed with a <I>cosine</I> potential. The assignment
of angle type to style is made via the <A HREF = "angle_coeff.html">angle_coeff</A>
command or in the data file.
</P>
<P>In the angle_coeff commands, the name of an angle style must be added
after the angle type, with the remaining coefficients being those
appropriate to that style. In the example above, the 2 angle_coeff
commands set angles of angle type 1 to be computed with a <I>harmonic</I>
potential with coefficients 80.0, 30.0 for K, theta0. All other angle
types (2-N) are computed with a <I>cosine</I> potential with coefficient
50.0 for K.
</P>
<P>If angle coefficients are specified in the data file read via the
<A HREF = "read_data.html">read_data</A> command, then the same rule applies.
E.g. "harmonic" or "cosine", must be added after the angle type, for each
line in the "Angle Coeffs" section, e.g.
</P>
<PRE>Angle Coeffs
</PRE>
<PRE>1 harmonic 80.0 30.0
2 cosine 50.0
...
</PRE>
<P>If <I>class2</I> is one of the angle hybrid styles, the same rule holds for
specifying additional BondBond (and BondAngle) coefficients either via
the input script or in the data file. I.e. <I>class2</I> must be added to
each line after the angle type. For lines in the BondBond (or
BondAngle) section of the data file for angle types that are not
<I>class2</I>, you must use an angle style of <I>skip</I> as a placeholder, e.g.
</P>
<PRE>BondBond Coeffs
</PRE>
<PRE>1 skip
2 class2 3.6512 1.0119 1.0119
...
</PRE>
<P>Note that it is not necessary to use the angle style <I>skip</I> in the
input script, since BondBond (or BondAngle) coefficients need not be
specified at all for angle types that are not <I>class2</I>.
</P>
<P>An angle style of <I>none</I> with no additional coefficients can be used
in place of an angle style, either in a input script angle_coeff
command or in the data file, if you desire to turn off interactions
for specific angle types.
</P>
<HR>
<P><B>Restrictions:</B>
</P>
<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.
</P>
<P>Unlike other angle styles, the hybrid angle style does not store angle
coefficient info for individual sub-styles in a <A HREF = "restart.html">binary restart
files</A>. Thus when retarting a simulation from a restart
file, you need to re-specify angle_coeff commands.
</P>
<P><B>Related commands:</B>
</P>
<P><A HREF = "angle_coeff.html">angle_coeff</A>
</P>
<P><B>Default:</B> none
</P>
</HTML>
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