fix nve/superquadric command¶

Syntax¶

fix ID group-ID nve/superquadric keyword value

ID, group-ID are documented in fix command
nve/superquadric = 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

integration_scheme values = 0, 1 or 2
  0 = based on Richardson iterations
  1 = symplectic algorithm (recommended)
  2 = leap-frog predictor-corrector
  3 = Woodem scheme

Examples¶

fix 1 all nve/superquadric 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 spherical particles and only updates their position and velocity.

This model is used in the framework of SUPERQUADRIC simulations. For more information see also the superquadric guide.

Restart, fix_modify, output, run start/stop, minimize info:

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. This fix is not invoked during energy minimization.

Restrictions¶

This fix requires atom_style superquadric.

All particles in the group must be finite-size. They cannot be point particles, but they can be aspherical/spherical as defined by their shape attribute.

Default¶

integration_scheme = 1

(Miller, 2002) Miller. et al., Journal of Chemical Physics, 116 (20), p 8649-8659 (2002)

(Walton, 1993) Walton and Braun, DOE/NSF Workshop on Flow of Particulates and Fluids, p 1-18 (1993)