forked from lijiext/lammps
106 lines
3.4 KiB
Plaintext
106 lines
3.4 KiB
Plaintext
.. index:: fix print
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fix print command
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=================
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Syntax
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""""""
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.. parsed-literal::
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fix ID group-ID print N string keyword value ...
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* ID, group-ID are documented in :doc:`fix <fix>` command
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* print = style name of this fix command
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* N = print every N steps
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* string = text string to print with optional variable names
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* zero or more keyword/value pairs may be appended
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* keyword = *file* or *append* or *screen* or *title*
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.. parsed-literal::
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*file* value = filename
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*append* value = filename
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*screen* value = *yes* or *no*
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*title* value = string
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string = text to print as 1st line of output file
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Examples
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""""""""
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.. parsed-literal::
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fix extra all print 100 "Coords of marker atom = $x $y $z"
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fix extra all print 100 "Coords of marker atom = $x $y $z" file coord.txt
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Description
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"""""""""""
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Print a text string every N steps during a simulation run. This can
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be used for diagnostic purposes or as a debugging tool to monitor some
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quantity during a run. The text string must be a single argument, so
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it should be enclosed in double quotes if it is more than one word.
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If it contains variables it must be enclosed in double quotes to
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insure they are not evaluated when the input script line is read, but
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will instead be evaluated each time the string is printed.
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The specified group-ID is ignored by this fix.
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See the :doc:`variable <variable>` command for a description of *equal*
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style variables which are the most useful ones to use with the fix
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print command, since they are evaluated afresh each timestep that the
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fix print line is output. Equal-style variables calculate formulas
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involving mathematical operations, atom properties, group properties,
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thermodynamic properties, global values calculated by a
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:doc:`compute <compute>` or :doc:`fix <fix>`, or references to other
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:doc:`variables <variable>`.
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If the *file* or *append* keyword is used, a filename is specified to
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which the output generated by this fix will be written. If *file* is
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used, then the filename is overwritten if it already exists. If
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*append* is used, then the filename is appended to if it already
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exists, or created if it does not exist.
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If the *screen* keyword is used, output by this fix to the screen and
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logfile can be turned on or off as desired.
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The *title* keyword allow specification of the string that will be
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printed as the first line of the output file, assuming the *file*
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keyword was used. By default, the title line is as follows:
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.. parsed-literal::
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# Fix print output for fix ID
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where ID is replaced with the fix-ID.
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Restart, fix_modify, output, run start/stop, minimize info
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""""""""""""""""""""""""""""""""""""""""""""""""""""""""""
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No information about this fix is written to :doc:`binary restart files <restart>`. None of the :doc:`fix_modify <fix_modify>` options
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are relevant to this fix. No global or per-atom quantities are stored
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by this fix for access by various :ref:`output commands <howto_15>`. No parameter of this fix can
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be used with the *start/stop* keywords of the :doc:`run <run>` command.
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This fix is not invoked during :doc:`energy minimization <minimize>`.
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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:`variable <variable>`, :doc:`print <print>`
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Default
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"""""""
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The option defaults are no file output, screen = yes, and title string
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as described above.
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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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