forked from lijiext/lammps
76 lines
2.7 KiB
HTML
76 lines
2.7 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>compute pe command
|
|
</H3>
|
|
<P><B>Syntax:</B>
|
|
</P>
|
|
<PRE>compute ID group-ID pe keyword ...
|
|
</PRE>
|
|
<UL><LI>ID, group-ID are documented in <A HREF = "compute.html">compute</A> command
|
|
<LI>pe = style name of this compute command
|
|
<LI>zero or more keywords may be appended
|
|
<LI>keyword = <I>pair</I> or <I>bond</I> or <I>angle</I> or <I>dihedral</I> or <I>improper</I> or <I>kspace</I>
|
|
</UL>
|
|
<P><B>Examples:</B>
|
|
</P>
|
|
<PRE>compute 1 all pe
|
|
compute molPE all pe bond angle dihedral improper
|
|
</PRE>
|
|
<P><B>Description:</B>
|
|
</P>
|
|
<P>Define a computation that calculates the potential energy of the
|
|
entire system of atoms. The specified group must be "all". See the
|
|
<A HREF = "compute_pe_atom.html">compute pe/atom</A> command if you want per-atom
|
|
energies. These per-atom values could be summed for a group of atoms
|
|
via the <A HREF = "compute_reduce.html">compute reduce</A> command.
|
|
</P>
|
|
<P>The energy is calculated by the various pair, bond, etc potentials
|
|
defined for the simulation. If no extra keywords are listed, then the
|
|
potential energy is the sum of pair, bond, angle, dihedral, improper,
|
|
and kspace (long-range) energy. If any extra keywords are listed,
|
|
then only those components are summed to compute the potential energy.
|
|
</P>
|
|
<P>Various fixes can contribute to the total potential energy of the
|
|
system. See the doc pages for <A HREF = "fix.html">individual fixes</A> for
|
|
details. The <I>thermo</I> option of the
|
|
<A HREF = "compute_modify.html">compute_modify</A> command determines whether these
|
|
contributions are added into the computed potential energy. If no
|
|
keywords are specified the default is <I>yes</I>. If any keywords are
|
|
specified, the default is <I>no</I>.
|
|
</P>
|
|
<P>A compute of this style with the ID of "thermo_pe" is created when
|
|
LAMMPS starts up, as if this command were in the input script:
|
|
</P>
|
|
<PRE>compute thermo_pe all pe
|
|
</PRE>
|
|
<P>See the "thermo_style" command for more details.
|
|
</P>
|
|
<P><B>Output info:</B>
|
|
</P>
|
|
<P>This compute calculates a global scalar (the potential energy). This
|
|
value can be used by any command that uses a global scalar value from
|
|
a compute as input. See <A HREF = "Section_howto.html#4_15">this section</A> for an
|
|
overview of LAMMPS output options.
|
|
</P>
|
|
<P>The scalar value calculated by this compute is "extensive". The
|
|
scalar value will be in energy <A HREF = "units.html">units</A>.
|
|
</P>
|
|
<P><B>Restrictions:</B> none
|
|
</P>
|
|
<P><B>Related commands:</B>
|
|
</P>
|
|
<P><A HREF = "compute_pe_atom.html">compute pe/atom</A>
|
|
</P>
|
|
<P><B>Default:</B> none
|
|
</P>
|
|
</HTML>
|