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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>compute force/molecule command
</H3>
<P><B>Syntax:</B>
</P>
<PRE>compute ID group-ID force/molecule
</PRE>
<UL><LI>ID, group-ID are documented in <A HREF = "compute.html">compute</A> command
<LI>force/molecule = style name of this compute command
</UL>
<P><B>Examples:</B>
</P>
<PRE>compute 1 fluid force/molecule
</PRE>
<P><B>Description:</B>
</P>
<P>Define a computation that calculates the total force on individual
molecules, as a sum over the forces on atoms in the molecule. The
x,y,z components of the force on each molecule are computed.
</P>
<P>The force on a particular molecule is only computed if one or more of
its atoms are in the specified group. Normally all atoms in the
molecule should be in the group, however this is not required. LAMMPS
will warn you if this is not the case. Only atoms in the group
contribute to the force on the molecule.
</P>
<P>The ordering of per-molecule quantities produced by this compute is
consistent with the ordering produced by other compute commands that
generate per-molecule datums. Conceptually, them molecule IDs will be
in ascending order for any molecule with one or more of its atoms in
the specified group.
</P>
<P><B>Output info:</B>
</P>
<P>This compute calculates a global array where the number of rows =
Nmolecules and the number of columns = 3 for the fx,fy,fz components
of force on each molecule. These values can be accessed by any
command that uses global array values from a compute as input. See
<A HREF = "Section_howto.html#howto_15">Section_howto 15</A> for an overview of
LAMMPS output options.
</P>
<P>The array values are "intensive". The array values will be in
distance <A HREF = "units.html">units</A>.
</P>
<P><B>Restrictions:</B> none
</P>
<P><B>Related commands:</B>
</P>
<P><A HREF = "compute_vcm_molecule.html">compute vcm/molecule</A>
</P>
<P><B>Default:</B> none
</P>
</HTML>
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