LAMMPS WWW Site - LAMMPS Documentation - LAMMPS Commands

### compute pe command

Syntax:

    compute ID group-ID pe keyword ...

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

Examples:

    compute 1 all pe
    compute molPE all pe bond angle dihedral improper

Description:

Define a computation that calculates the potential energy of the entire system of atoms. The specified group must be "all". See the compute pe/atom command if you want per-atom energies. These per-atom values could be summed for a group of atoms via the compute reduce command.

The energy is calculated 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, improper, and kspace (long-range) energy. If any extra keywords are listed, then only those components are summed to compute the potential energy.

Various fixes can contribute to the total potential energy of the system. See the doc pages for individual fixes for details. The thermo option of the compute_modify command determines whether these contributions are added into the computed potential energy. If no keywords are specified the default is yes. If any keywords are specified, the default is no.

A compute of this style with the ID of "thermo_pe" is created when LAMMPS starts up, as if this command were in the input script:

    compute thermo_pe all pe

See the "thermo_style" command for more details.

Output info:

This compute calculates a global scalar (the potential energy). 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: none

Related commands:

compute pe/atom

Default: none