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compute_temp_partial.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>
</CENTER>
<HR>
<H3>compute temp/partial command
</H3>
<P><B>Syntax:</B>
</P>
<PRE>compute ID group-ID temp/partial xflag yflag zflag
</PRE>
<UL><LI>ID, group-ID are documented in <A HREF = "compute.html">compute</A> command
<LI>temp/partial = style name of this compute command
<LI>xflag,yflag,zflag = 0/1 for whether to exclude/include this dimension
</UL>
<P><B>Examples:</B>
</P>
<PRE>compute newT flow temp/partial 1 1 0
</PRE>
<P><B>Description:</B>
</P>
<P>Define a compute to calculate the temperature of a group of atoms,
after excluding one or more velocity components. 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>, <A HREF = "fix_npt.html">fix npt</A>, etc.
</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 = dimensionality of the simulation, N = number of atoms in the
group, k = Boltzmann constant, and T = temperature. The calculation
of KE excludes the x, y, or z dimensions if xflag, yflag, or zflag =
0. The dim parameter is adjusted to give the correct number of
degrees of freedom.
</P>
<P>A 6-component kinetic energy tensor is also calculated by this compute
for use in the calculation 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 assumed to be
constant for the duration of the run; use the <I>dynamic</I> option of the
<A HREF = "compute_modify.html">compute_modify</A> command if this is not the case.
</P>
<P>This compute subtracts 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>. This means the temperature of groups of
atoms that include these constraints will be computed correctly. 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_temp_region.html">compute
temp/region</A>, <A HREF = "compute_pressure.html">compute
pressure</A>
</P>
<P><B>Default:</B> none
</P>
</HTML>

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