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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 temp/region command
</H3>
<P><B>Syntax:</B>
</P>
<PRE>compute ID group-ID temp/region region-ID
</PRE>
<UL><LI>ID, group-ID are documented in <A HREF = "compute.html">compute</A> command
<LI>temp/region = style name of this compute command
<LI>region-ID = ID of region to use for choosing atoms
</UL>
<P><B>Examples:</B>
</P>
<PRE>temperature mine flow region boundary
</PRE>
<P><B>Description:</B>
</P>
<P>Define a computation that calculates the temperature of a group of
atoms in a geometric region. This can be useful for thermostatting
one portion of the simulation box. E.g. a McDLT simulation where one
side is cooled, and the other side is heated. A compute of this style
can be used by any command that computes a temperature,
e.g. <A HREF = "thermo_modify.html">thermo_modify</A>, <A HREF = "fix_temp_rescale.html">fix
temp/rescale</A>, etc.
</P>
<P>Note that a <I>region</I>-style temperature can be used to thermostat with
<A HREF = "fix_temp_rescale.html">fix temp/rescale</A> or <A HREF = "fix_langevin.html">fix
langevin</A>, but should probably not be used with
Nose/Hoover style fixes (<A HREF = "fix_nvt.html">fix nvt</A>, <A HREF = "fix_npt.html">fix
npt</A>, or <A HREF = "fix_nph.html">fix nph</A>), if the
degrees-of-freedom included in the computed T varies with time.
</P>
<P>The temperature is calculated by the formula KE = dim/2 N k T, where
KE = total kinetic energy of the group of atoms (sum of 1/2 m v^2),
dim = 2 or 3 = dimensionality of the simulation, N = number of atoms
in both the group and region, k = Boltzmann constant, and T =
temperature.
</P>
<P>A 6-component kinetic energy tensor is also calculated by this compute
for use in the computation of a pressure tensor. The formula for the
components of the tensor is the same as the above formula, except that
v^2 is replaced by vx * vy for the xy component, etc.
</P>
<P>The number of atoms contributing to the temperature is compute each
time the temperature is evaluated since it is assumed atoms can
enter/leave the region. Thus there is no need to use the <I>dynamic</I>
option of the <A HREF = "compute_modify.html">compute_modify</A> command for this
compute style.
</P>
<P>Unlike other compute styles that calculate temperature, this compute
does NOT currently subtract out degrees-of-freedom due to fixes that
constrain molecular motion, such as <A HREF = "fix_shake.html">fix shake</A> and
<A HREF = "fix_rigid.html">fix rigid</A>. If needed the subtracted
degrees-of-freedom can be altered using the <I>extra</I> option of the
<A HREF = "compute_modify.html">compute_modify</A> command.
</P>
<P><B>Restrictions:</B> none
</P>
<P><B>Related commands:</B>
</P>
<P><A HREF = "compute_temp.html">compute temp</A>, <A HREF = "compute_pressure.html">compute
pressure</A>
</P>
<P><B>Default:</B> none
</P>
</HTML>
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