limit command¶

Syntax¶

fix ID group-ID nve/sphere/limit

ID, group-ID are documented in fix command
nve/sphere/limit = style name of this fix command
zero or more keyword/value pairs may be appended
keyword = update or vlimit or omegalimit

update value = dipole
  dipole = update orientation of dipole moment during integration
vlimit value = vmax
  vmax = maximum velocity with which an atom can move
omegalimit value = omegamax
  omegamax = maximum angular velocity with which an atom can rotate

Examples¶

fix 1 all nve/sphere/limit
fix 1 all nve/sphere/limit update dipole

Description¶

Perform constant NVE integration similar to fix nve/sphere to update position, velocity, and angular velocity for finite-size spherical particles in the group each timestep.

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.

Similar to fix nve/limit for point atoms, this fix uses the keywords vlimit and omegalimit to define a maximum velocity and maximum angular velocity for finite-size spherical atoms. This is useful when starting a simulation with a configuration containing highly overlapped atoms. Normally this would generate huge forces which would blow atoms out of the simulation box.

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.

This fix computes a scalar which can be accessed by various output commands. This scalar is the total number of limited atoms of the fix group.

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 that atoms store torque and angular velocity (omega) and a radius as defined by the atom_style sphere command. If the dipole keyword is used, then they must also store a dipole moment as defined by the atom_style dipole command.

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