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fix_manifoldforce.txt
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.. index:: fix manifoldforce
fix manifoldforce command
=========================
Syntax
""""""
.. parsed-literal::
fix ID group-ID manifoldforce manifold manifold-args ...
* ID, group-ID are documented in :doc:`fix <fix>` command
* manifold = name of the manifold
* manifold-args = parameters for the manifold
Examples
""""""""
fix constrain all manifoldforce sphere 5.0
Description
"""""""""""
This fix subtracts each time step from the force the component along the normal of the specified :doc:`manifold <manifolds>`.
This can be used in combination with :doc:`minimize <minimize>` to remove overlap between particles while
keeping them (roughly) constrained to the given manifold, e.g. to set up a run with :doc:`fix nve/manifold/rattle <fix_nve_manifold_rattle>`.
I have found that only *hftn* and *quickmin* with a very small time step perform adequately though.
----------
Restart, fix_modify, output, run start/stop, minimize info
""""""""""""""""""""""""""""""""""""""""""""""""""""""""""
No information about this fix is written to :doc:`binary restart files <restart>`. None of the :doc:`fix_modify <fix_modify>` options
are relevant to this fix. No global or per-atom quantities are stored
by this fix for access by various :ref:`output commands <howto_15>`. No parameter of this fix can
be used with the *start/stop* keywords of the :doc:`run <run>` command.
This fix is invoked during :doc:`energy minimization <minimize>`.
----------
Restrictions
""""""""""""
This fix is part of the USER-MANIFOLD package. It is only enabled if LAMMPS
was built with that package. See the :ref:`Making LAMMPS <start_3>`
section for more info.
Only use this with *min_style hftn* or *min_style quickmin*\ . If not, the constraints
will not be satisfied very well at all. A warning is generated if the *min_style* is
incompatible but no error.
----------
Related commands
""""""""""""""""
:doc:`fix nve/manifold/rattle <fix_nve_manifold_rattle>`, :doc:`fix nvt/manifold/rattle <fix_nvt_manifold_rattle>`
.. _lws: http://lammps.sandia.gov
.. _ld: Manual.html
.. _lc: Section_commands.html#comm
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