fix nve/nonspherical command

Syntax

fix ID group-ID nve/nonspherical keyword value

• ID, group-ID are documented in fix command

• nve/nonspherical = style name of this fix command

• zero or one keyword/value pair may be appended to args; the dim keyword must be used

• keyword = integration_scheme or update

integration_scheme values = 0, 1 or 2
  0 = based on Richardson iterations
  1 = symplectic algorithm (recommended)
  2 = leap-frog predictor-corrector
  3 = Woodem scheme
update arg = dipole
  dipole = update orientation of dipole moment (mu) during integration

Examples

fix 1 all nve/nonspherical integration_scheme 1

Description

Perform constant NVE integration to update position, velocity, orientation, and angular velocity for superquadric particles in the group each timestep. V is volume; E is energy. This creates a system trajectory consistent with the microcanonical ensemble.

This fix differs from the fix nve/sphere command, which assumes point particles and only updates their position and velocity.

This model is used in the framework of Multispherical, Superquadric, Convex and Concave simulations. For more information see also the SUPERQUADRIC guide or Convex guide or Concave guide.

If the update keyword is used with the dipole value, then the orientation of the dipole moment of each particle is also updated during the time integration. This option should be used for models where a dipole moment is assigned to particles via use of the atom_style dipole command.

Restart, fix_modify, output, run start/stop

No information about this fix is written to binary restart files. None of the fix_modify options are relevant to this fix. No global or per-atom quantities are stored by this fix for access by various output commands. No parameter of this fix can be used with the start/stop keywords of the run command.

Restrictions

This fix requires atom_style superquadric or fix multisphere or atom_style convex.

All particles in the group must be finite-size. They cannot be point particles.

Related commands

fix nve, fix nve/sphere

Default

integration_scheme = 1

( `Miller <http://scitation.aip.org/content/aip/journal/jcp/116/20/10.1063/1.1473654>`_ ) Miller. et al., Journal of Chemical Physics, 116 (20), p 8649-8659 (2002)

( `Walton <http://www.grainflow.com/index_files/Rotary_Drum_Simulation_DOE-NSF-1993.pdf>`_ ) Walton and Braun, DOE/NSF Workshop on Flow of Particulates and Fluids, p 1-18 (1993)