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compute_modify.txt
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.. index:: compute_modify
compute_modify command
======================
Syntax
""""""
.. parsed-literal::
compute_modify compute-ID keyword value ...
* compute-ID = ID of the compute to modify
* one or more keyword/value pairs may be listed
* keyword = *extra* or *dynamic*
.. parsed-literal::
*extra* value = N
N = # of extra degrees of freedom to subtract
*dynamic* value = *yes* or *no*
yes/no = do or do not recompute the number of atoms contributing to the temperature
Examples
""""""""
.. parsed-literal::
compute_modify myTemp extra 0
compute_modify newtemp dynamic yes extra 600
Description
"""""""""""
Modify one or more parameters of a previously defined compute. Not
all compute styles support all parameters.
The *extra* 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 :doc:`2d or 3d systems <dimension>` which is a correction factor for an ensemble
of velocities with zero total linear momentum. For compute
temp/partial, if one or more velocity components are excluded, the
value used for *extra* is scaled accordingly. You can use a negative
number for the *extra* parameter if you need to add
degrees-of-freedom. See the :doc:`compute temp/asphere <compute_temp_asphere>` command for an example.
The *dynamic* 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 calculate a temperature use this option. By
default, N is assumed to be constant. If you are adding atoms to the
system (see the :doc:`fix pour <fix_pour>` or :doc:`fix deposit <fix_deposit>` 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.
Restrictions
""""""""""""
none
Related commands
""""""""""""""""
:doc:`compute <compute>`
Default
"""""""
The option defaults are extra = 2 or 3 for 2d or 3d systems and
dynamic = no.
.. _lws: http://lammps.sandia.gov
.. _ld: Manual.html
.. _lc: Section_commands.html#comm
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