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### fix nve/sphere command

Syntax:

    fix ID group-ID nve/sphere

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

        update value = dipole
          dipole = update orientation of dipole moment during integration

Examples:

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

Description:

Perform constant NVE integration to update position, velocity, and angular velocity for extended spherical 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 command, which assumes point particles and only updates their position and velocity.

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 the dipole command.

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 scalar or vector 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 that particles be represented as extended spheres and not point particles. This means they will have an angular velocity and a diameter which is determined either by the shape command or by each particle being assigned an individual radius, e.g. for atom_style granular.

Related commands:

fix nve, fix nve/asphere

Default: none