64 lines
2.0 KiB
ReStructuredText
64 lines
2.0 KiB
ReStructuredText
.. index:: fix manifoldforce
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fix manifoldforce 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 manifoldforce manifold manifold-args ...
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* ID, group-ID are documented in :doc:`fix <fix>` command
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* manifold = name of the manifold
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* manifold-args = parameters for the manifold
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Examples
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""""""""
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.. code-block:: LAMMPS
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fix constrain all manifoldforce sphere 5.0
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Description
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"""""""""""
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This fix subtracts each time step from the force the component along
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the normal of the specified :doc:`manifold <Howto_manifold>`. This can be
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used in combination with :doc:`minimize <minimize>` to remove overlap
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between particles while keeping them (roughly) constrained to the
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given manifold, e.g. to set up a run with :doc:`fix nve/manifold/rattle <fix_nve_manifold_rattle>`. I have found that
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only *hftn* and *quickmin* with a very small time step perform
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adequately though.
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----------
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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 :doc:`output commands <Howto_output>`.
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No parameter of this fix can be used with the *start/stop* keywords of
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the :doc:`run <run>` command. This fix is invoked during :doc:`energy minimization <minimize>`.
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----------
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Restrictions
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""""""""""""
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This fix is part of the MANIFOLD package. It is only enabled if
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LAMMPS was built with that package. See the :doc:`Build package <Build_package>` page for more info.
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Only use this with *min_style hftn* or *min_style quickmin*. If not,
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the constraints will not be satisfied very well at all. A warning is
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generated if the *min_style* is incompatible but no error.
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----------
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Related commands
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""""""""""""""""
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:doc:`fix nve/manifold/rattle <fix_nve_manifold_rattle>`, :doc:`fix nvt/manifold/rattle <fix_nvt_manifold_rattle>`
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