LAMMPS WWW Site - LAMMPS Documentation - LAMMPS Commands

### compute erotate/sphere command

Syntax:

    compute ID group-ID erotate/sphere

- ID, group-ID are documented in compute command
- erotate/sphere = style name of this compute command

Examples:

    compute 1 all erotate/sphere

Description:

Define a computation that calculates the rotational kinetic energy of a group of spherical particles.

The rotational energy is computed as 1/2 I w^2, where I is the moment of inertia for a sphere and w is the particle's angular velocity.

IMPORTANT NOTE: For 2d models, particles are treated as spheres, not disks, meaning their moment of inertia will be the same as in 3d.

Output info:

This compute calculates a global scalar (the KE). This value can be used by any command that uses a global scalar value from a compute as input. See this section for an overview of LAMMPS output options.

The scalar value calculated by this compute is "extensive". The scalar value will be in energy units.

Restrictions:

This compute requires that atoms store angular velocity (omega) as defined by the atom_style. It also require they store either a per-particle diameter or per-type shape.

All particles in the group must be finite-size spheres or point particles. They cannot be aspherical. Point particles will not contribute to the rotational energy.

Related commands:

compute erotate/asphere

Default: none