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### compute pe/atom command

Syntax:

    compute ID group-ID pe/atom keyword ...

- ID, group-ID are documented in compute command
- pe/atom = style name of this compute command
- zero or more keywords may be appended
- keyword = pair or bond or angle or dihedral or improper

Examples:

    compute 1 all pe/atom
    compute 1 all pe/atom pair
    compute 1 all pe/atom pair bond

Description:

Define a computation that computes the per-atom potential energy for each atom in a group. See the compute pe command if you want the potential energy of the entire system. The per-atom energies can be accessed as scalar values by any command that uses per-atom computes, e.g. the dump custom command or fix ave/spatial command or fix ave/atom command. See this section for an overview.

The per-atom energy is calulated by the various pair, bond, etc potentials defined for the simulation. If no extra keywords are listed, then the potential energy is the sum of pair, bond, angle, dihedral, and improper energy. If any extra keywords are listed, then only those components are summed to compute the potential energy.

Note that the energy of each atom is due to its interaction with all other atoms in the simulation, not just with other atoms in the group.

For an energy contribution produced by a small set of atoms (e.g. 4 atoms in a dihedral or 3 atoms in a Tersoff 3-body interaction), that energy is assigned in equal portions to each atom in the set. E.g. 1/4 of the dihedral energy to each of the 4 atoms.

The dihedral_style charmm style calculates pairwise interactions between 1-4 atoms. The energy contribution of these terms is included in the pair energy, not the dihedral energy.

Restrictions: none

Related commands:

compute pe, compute stress/atom

Default: none