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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>
</CENTER>
<HR>
<H3>compute command
</H3>
<P><B>Syntax:</B>
</P>
<PRE>compute ID group-ID style args
</PRE>
<UL><LI>ID = user-assigned name for the computation
<LI>group-ID = ID of the group of atoms to perform the computation on
<LI>style = one of a list of possible style names (see below)
<LI>args = arguments used by a particular style
</UL>
<P><B>Examples:</B>
</P>
<PRE>compute 1 all temp
compute newtemp flow temp/partial 1 1 0
compute 3 all ke/atom
</PRE>
<P><B>Description:</B>
</P>
<P>Create a computation that will be performed on a group of atoms.
</P>
<P>In LAMMPS, a "compute" is used in several ways. There are two kinds
of computes, "global" computes that calculate one or more values for
the entire group of atoms, and "per-atom" computes that calculate one
or more values for each atom in the group. The latter has the word
"atom" in its style name.
</P>
<P>The results of global computes can be output via the <A HREF = "thermo_style.html">thermo_style
custom</A> or <A HREF = "fix_ave_time.html">fix ave/time</A> command.
Or the values can be referenced in a <A HREF = "variable.html">variable equal</A>
command. The results of computes that calculate a global temperature
or pressure can be used by fixes that do thermostatting or
barostatting and when atom velocities are created.
</P>
<P>The results of per-atom computes can be output via the <A HREF = "dump.html">dump
custom</A> command or the <A HREF = "fix_ave_spatial.html">fix
ave/spatial</A> command. Or the per-atom values can
be time-averaged via the <A HREF = "fix_ave_atom.html">fix ave/atom</A> command and
then output via the <A HREF = "dump.html">dump custom</A> or <A HREF = "fix_ave_spatial.html">fix
ave/spatial</A> commands.
</P>
<P>LAMMPS creates its own global computes for thermodynamic output. Two
computes are always created, named "thermo_temp" and
"thermo_pressure", as if these commands had been invoked:
</P>
<PRE>compute thermo_temp all temp
compute thermo_pressure all pressure thermo_temp
</PRE>
<P>Additional computes are created if the thermo style requires it. See
the documentation for the <A HREF = "thermo_style.html">thermo_style</A> command.
</P>
<P>The dumping of atom snapshots and fixes that compute temperature or
pressure also create computes as required. These are discussed in the
documentation for the <A HREF = "dump.html">dump custom</A> and specific
<A HREF = "fix.html">fix</A> commands.
</P>
<P>In all these cases, the default computes can be replaced by computes
defined by the user in the input script, as described by the
<A HREF = "thermo_modify.html">thermo_modify</A>, <A HREF = "fix_modify.html">fix modify</A>, and
<A HREF = "dump.html">dump</A> commands.
</P>
<P>Properties of either a default of user-defined compute can be modified
via the <A HREF = "compute_modify.html">compute_modify</A> command.
</P>
<P>Computes can be deleted with the <A HREF = "uncompute.html">uncompute</A> command.
</P>
<P>Code for new computes can be added to LAMMPS (see <A HREF = "Section_modify.html">this
section</A> of the manaul) and the results of their
calculations accessed in the various ways described above.
</P>
<P>Each compute style has its own doc page which describes its arguments
and what it does. Here is an alphabetic list of compute styles
defined in LAMMPS:
</P>
<UL><LI><A HREF = "compute_attribute_atom.html">attribute/atom</A> - attribute (x,v,f,etc) of each atom
<LI><A HREF = "compute_centro_atom.html">centro/atom</A> - centro-symmetry parameter for each atom
<LI><A HREF = "compute_coord_atom.html">coord/atom</A> - coordination number for each atom
<LI><A HREF = "compute_ebond_atom.html">ebond/atom</A> - bond energy for each atom
<LI><A HREF = "compute_epair_atom.html">epair/atom</A> - pairwise energy for each atom
<LI><A HREF = "compute_ke_atom.html">ke/atom</A> - kinetic energy for each atom
<LI><A HREF = "compute_pressure.html">pressure</A> - total pressure and pressure tensor
<LI><A HREF = "compute_rotate_dipole.html">rotate/dipole</A> - rotational energy of dipolar atoms
<LI><A HREF = "compute_rotate_gran.html">rotate/gran</A> - rotational energy of granular atoms
<LI><A HREF = "compute_stress_atom.html">stress/atom</A> - stress tensor for each atom
<LI><A HREF = "compute_sum_atom.html">sum/atom</A> - sum 2 or more quantities for each atom
<LI><A HREF = "compute_temp.html">temp</A> - temperature of group of atoms
<LI><A HREF = "compute_temp_asphere.html">temp/asphere</A> - temperature of aspherical particles
<LI><A HREF = "compute_temp_deform.html">temp/deform</A> - temperature excluding box deformation velocity
<LI><A HREF = "compute_temp_dipole.html">temp/dipole</A> - temperature of point dipolar particles
<LI><A HREF = "compute_temp_partial.html">temp/partial</A> - temperature excluding one or more dimensions of velocity
<LI><A HREF = "compute_temp_ramp.html">temp/ramp</A> - temperature excluding ramped velocity component
<LI><A HREF = "compute_temp_region.html">temp/region</A> - temperature of a region of atoms
<LI><A HREF = "compute_variable.html">variable</A> - calculate a scalar value from a variable
<LI><A HREF = "compute_variable_atom.html">variable/atom</A> - calculate a formula for each atom
</UL>
<P><B>Restrictions:</B> none
</P>
<P><B>Related commands:</B>
</P>
<P><A HREF = "uncompute.html">uncompute</A>, <A HREF = "compute_modify.html">compute_modify</A>
</P>
<P><B>Default:</B> none
</P>
</HTML>

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