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