forked from lijiext/lammps
97 lines
3.0 KiB
HTML
97 lines
3.0 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 gauss command
|
|
</H3>
|
|
<P><B>Syntax:</B>
|
|
</P>
|
|
<PRE>pair_style gauss cutoff
|
|
</PRE>
|
|
<UL><LI>cutoff = global cutoff for Gauss interactions (distance units)
|
|
</UL>
|
|
<P><B>Examples:</B>
|
|
</P>
|
|
<PRE>pair_style gauss 12.0
|
|
pair_coeff * * 1.0 0.9
|
|
pair_coeff 1 4 1.0 0.9 10.0
|
|
</PRE>
|
|
<P><B>Description:</B>
|
|
</P>
|
|
<P>Style <I>gauss</I> computes a tethering potential of the form
|
|
</P>
|
|
<CENTER><IMG SRC = "Eqs/pair_gauss.jpg">
|
|
</CENTER>
|
|
<P>between an atom and its corresponding tether site which will typically
|
|
be a frozen atom in the simulation. Rc is the cutoff.
|
|
</P>
|
|
<P>The following coefficients must be defined for each pair of atom 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>A (energy units)
|
|
<LI>B (1/distance^2 units)
|
|
<LI>cutoff (distance units)
|
|
</UL>
|
|
<P>The last coefficient is optional. If not specified, the global cutoff
|
|
is used.
|
|
</P>
|
|
<HR>
|
|
|
|
<P><B>Mixing, shift, table, tail correction, restart, rRESPA info</B>:
|
|
</P>
|
|
<P>This pair style does not support mixing. Thus, coefficients for all
|
|
I,J pairs must be specified explicitly.
|
|
</P>
|
|
<P>This pair style does not support the <A HREF = "pair_modify.html">pair_modify</A>
|
|
shift option. There is no effect due to the Gaussian well beyond the
|
|
cutoff; hence reasonable cutoffs need to be specified.
|
|
</P>
|
|
<P>The <A HREF = "pair_modify.html">pair_modify</A> table and tail options are not
|
|
relevant for this pair style.
|
|
</P>
|
|
<P>This pair style does not support the <A HREF = "pair_modify.html">pair_modify</A>
|
|
table option, since a tabulation capability does not exist for this
|
|
potential.
|
|
</P>
|
|
<P>This pair style writes its information to <A HREF = "restart.html">binary restart
|
|
files</A>, so pair_style and pair_coeff commands do not need
|
|
to be specified in an input script that reads a restart file.
|
|
</P>
|
|
<P>This pair style can only be used via the <I>pair</I> keyword of the
|
|
<A HREF = "run_style.html">run_style respa</A> command. It does not support the
|
|
<I>inner</I>, <I>middle</I>, <I>outer</I> keywords.
|
|
</P>
|
|
<P>This pair style tallies an "occupancy" count of how many Gaussian-well
|
|
sites have an atom within the distance at which the force is a maximum
|
|
= sqrt(0.5/b). This quantity can be accessed via the <A HREF = "compute_pair.html">compute
|
|
pair</A> command as a vector of values of length 1.
|
|
</P>
|
|
<P>To print this quantity to the log file (with a descriptive column
|
|
heading) the following commands could be included in an input script:
|
|
</P>
|
|
<PRE>compute gauss all pair gauss
|
|
variable occ equal c_gauss[1]
|
|
thermo_style custom step temp epair v_occ
|
|
</PRE>
|
|
<HR>
|
|
|
|
<P><B>Restrictions:</B> none
|
|
</P>
|
|
<P><B>Related commands:</B>
|
|
</P>
|
|
<P><A HREF = "pair_coeff.html">pair_coeff</A>
|
|
</P>
|
|
<P><B>Default:</B> none
|
|
</P>
|
|
</HTML>
|