forked from lijiext/lammps
58 lines
1.6 KiB
ReStructuredText
58 lines
1.6 KiB
ReStructuredText
.. index:: fix nve/noforce
|
|
|
|
fix nve/noforce command
|
|
=======================
|
|
|
|
Syntax
|
|
""""""
|
|
|
|
.. parsed-literal::
|
|
|
|
fix ID group-ID nve
|
|
|
|
* ID, group-ID are documented in :doc:`fix <fix>` command
|
|
* nve/noforce = style name of this fix command
|
|
|
|
Examples
|
|
""""""""
|
|
|
|
.. code-block:: LAMMPS
|
|
|
|
fix 3 wall nve/noforce
|
|
|
|
Description
|
|
"""""""""""
|
|
|
|
Perform updates of position, but not velocity for atoms in the group
|
|
each timestep. In other words, the force on the atoms is ignored and
|
|
their velocity is not updated. The atom velocities are used to update
|
|
their positions.
|
|
|
|
This can be useful for wall atoms, when you set their velocities, and
|
|
want the wall to move (or stay stationary) in a prescribed fashion.
|
|
|
|
This can also be accomplished via the :doc:`fix setforce <fix_setforce>`
|
|
command, but with fix nve/noforce, the forces on the wall atoms are
|
|
unchanged, and can thus be printed by the :doc:`dump <dump>` command or
|
|
queried with an equal-style :doc:`variable <variable>` that uses the
|
|
fcm() group function to compute the total force on the group of atoms.
|
|
|
|
**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 :doc:`output commands <Howto_output>`.
|
|
No parameter of this fix can be used with the *start/stop* keywords of
|
|
the :doc:`run <run>` command. This fix is not invoked during :doc:`energy minimization <minimize>`.
|
|
|
|
Restrictions
|
|
""""""""""""
|
|
none
|
|
|
|
Related commands
|
|
""""""""""""""""
|
|
|
|
:doc:`fix nve <fix_nve>`
|
|
|
|
**Default:** none
|