forked from lijiext/lammps
59 lines
1.8 KiB
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59 lines
1.8 KiB
HTML
<HTML>
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<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>
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<HR>
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<H3>compute epair/atom command
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</H3>
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<P><B>Syntax:</B>
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</P>
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<PRE>compute ID group-ID epair/atom
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</PRE>
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<UL><LI>ID, group-ID are documented in <A HREF = "compute.html">compute</A> command
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<LI>epair/atom = style name of this compute command
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</UL>
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<P><B>Examples:</B>
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</P>
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<PRE>compute 1 all epair/atom
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</PRE>
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<P><B>Description:</B>
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</P>
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<P>Define a computation that computes the per-atom pairwise energy for
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each atom in a group.
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</P>
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<P>The pairwise energy for each atom is computed by looping over its
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neighbors and computing the energy associated with the defined
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<A HREF = "pair_style.html">pair_style</A> command for each I,J pair (divided by 2).
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Thus the sum of per-atom energy for all atoms should give the total
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pairwise energy of the system.
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</P>
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<P>If two atoms interact and only one of them is in the compute group,
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the energy of the pairwise interaction is included in the per-atom
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energy of the atom in the group.
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</P>
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<P>For force fields that include a contribution to the pairwise energy
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that is computed as part of dihedral terms (i.e. 1-4 interactions),
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this contribution is NOT included in the per-atom pairwise energy.
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</P>
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<P>Computation of per-atom pairwise energy requires a loop thru the
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neighbor list and inter-processor communication, so it can be
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inefficient to compute/dump this quantity too frequently or to have
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multiple compute/dump commands, each of a <I>epair/atom</I> style.
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</P>
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<P><B>Restrictions:</B>
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</P>
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<P>Some pair potentials do not allow the calculation of per-atom energy
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via this command. An error will be generated if this is the case.
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</P>
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<P><B>Related commands:</B> none
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</P>
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<P><B>Default:</B> none
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</P>
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</HTML>
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