forked from lijiext/lammps
97 lines
3.4 KiB
HTML
97 lines
3.4 KiB
HTML
<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>
|