forked from lijiext/lammps
73 lines
2.0 KiB
HTML
73 lines
2.0 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>pair_style morse command
|
|
</H3>
|
|
<H3>pair_style morse/opt command
|
|
</H3>
|
|
<P><B>Syntax:</B>
|
|
</P>
|
|
<PRE>pair_style morse cutoff
|
|
</PRE>
|
|
<UL><LI>cutoff = global cutoff for Morse interactions (distance units)
|
|
</UL>
|
|
<P><B>Examples:</B>
|
|
</P>
|
|
<PRE>pair_style morse 2.5
|
|
pair_style morse/opt 2.5
|
|
pair_coeff * * 100.0 2.0 1.5
|
|
pair_coeff 1 1 100.0 2.0 1.5 3.0
|
|
</PRE>
|
|
<P><B>Description:</B>
|
|
</P>
|
|
<P>Style <I>morse</I> computes pairwise interactions with the formula
|
|
</P>
|
|
<CENTER><IMG SRC = "Eqs/pair_morse.jpg">
|
|
</CENTER>
|
|
<P>Rc is the cutoff.
|
|
</P>
|
|
<P>The following coefficients must be defined for each pair of atoms
|
|
types via the <A HREF = "pair_coeff.html">pair_coeff</A> command as in the examples
|
|
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>D0 (energy units)
|
|
<LI>alpha (1/distance units)
|
|
<LI>r0 (distance units)
|
|
<LI>cutoff (distance units)
|
|
</UL>
|
|
<P>The last coefficient is optional. If not specified, the global morse
|
|
cutoff is used.
|
|
</P>
|
|
<P>Style <I>morse/opt</I> is an optimized version of style <I>morse</I> that should
|
|
give identical answers. Depending on system size and the processor
|
|
you are running on, it may be 5-25% faster (for the pairwise portion
|
|
of the run time).
|
|
</P>
|
|
<P><B>Restrictions:</B>
|
|
</P>
|
|
<P>The <I>morse</I> potential does not support the
|
|
<A HREF = "pair_modify.hmtl">pair_modify</A> <I>mix</I> option. Coefficients for all i,j
|
|
pairs must be specified explicitly.
|
|
</P>
|
|
<P>The <I>morse/opt</I> style is part of the "opt" package. It is only
|
|
enabled if LAMMPS was built with that package. See the <A HREF = "Section_start.html#2_3">Making
|
|
LAMMPS</A> section for more info.
|
|
</P>
|
|
<P><B>Related commands:</B>
|
|
</P>
|
|
<P><A HREF = "pair_coeff.html">pair_coeff</A>
|
|
</P>
|
|
<P><B>Default:</B> none
|
|
</P>
|
|
</HTML>
|