compute erotate/sphere command¶
Syntax¶
compute ID group-ID erotate/sphere general_keywords general_values halfstep
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. By default the angular velocity is taken at the full time step (w^i). If the halfstep keyword is present in the definition of this compute, then the angular velocity is taken at the next half time step (w^(i+1/2)).
Warning
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 Section_howto 15 for an overview of LIGGGHTS(R)-PUBLIC 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 a radius and angular velocity (omega) as defined by the atom_style sphere command.
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.