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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>
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<H3>compute_modify command
</H3>
<P><B>Syntax:</B>
</P>
<PRE>compute_modify compute-ID keyword value ...
</PRE>
<UL><LI>compute-ID = ID of the compute to modify
<LI>one or more keyword/value pairs may be listed
<LI>keyword = <I>extra</I> or <I>dynamic</I>
<PRE> <I>extra</I> value = N
N = # of extra degrees of freedom to subtract
<I>dynamic</I> value = <I>yes</I> or <I>no</I>
yes/no = do or do not recompute the number of atoms contributing to the temperature
<I>thermo</I> value = <I>yes</I> or <I>no</I>
yes/no = do or do not add contributions from fixes to the potential energy
</PRE>
</UL>
<P><B>Examples:</B>
</P>
<PRE>compute_modify myTemp extra 0
compute_modify newtemp dynamic yes extra 600
</PRE>
<P><B>Description:</B>
</P>
<P>Modify one or more parameters of a previously defined compute. Not
all compute styles support all parameters.
</P>
<P>The <I>extra</I> keyword refers to how many degrees-of-freedom are
subtracted (typically from 3N) as a normalizing factor in a
temperature computation. Only computes that compute a temperature use
this option. The default is 2 or 3 for <A HREF = "dimension.html">2d or 3d
systems</A> which is a correction factor for an ensemble
of velocities with zero total linear momentum. You can use a negative
number for the <I>extra</I> parameter if you need to add
degrees-of-freedom. See the <A HREF = "compute_temp_asphere.html">compute
temp/asphere</A> command for an example.
</P>
<P>The <I>dynamic</I> keyword determines whether the number of atoms N in the
compute group is re-computed each time a temperature is computed.
Only compute styles that compute a temperature use this option. By
default, N is assumed to be constant. If you are adding atoms to the
system (see the <A HREF = "fix_pour.html">fix pour</A> or <A HREF = "fix_deposit.html">fix
deposit</A> commands) or expect atoms to be lost
(e.g. due to evaporation), then this option should be used to insure
the temperature is correctly normalized.
</P>
<P>The <I>thermo</I> keyword determines whether the potential energy
contribution calculated by some <A HREF = "fix.html">fixes</A> is added to the
potential energy calculated by the compute. Currently, only the
compute of style <I>pe</I> uses this option. See the doc pages for
<A HREF = "fix.html">individual fixes</A> for details.
</P>
<P><B>Restrictions:</B> none
</P>
<P><B>Related commands:</B>
</P>
<P><A HREF = "compute.html">compute</A>
</P>
<P><B>Default:</B>
</P>
<P>The option defaults are extra = 2 or 3 for 2d or 3d systems and
dynamic = no. Thermo is <I>yes</I> if the compute of style <I>pe</I> was
defined with no extra keywords; otherwise it is <I>no</I>.
</P>
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