"LAMMPS WWW Site"_lws - "LAMMPS Documentation"_ld - "LAMMPS Commands"_lc :c

:link(lws,http://lammps.sandia.gov)
:link(ld,Manual.html)
:link(lc,Commands_all.html)

:line

compute ke command :h3

[Syntax:]

compute ID group-ID ke :pre

ID, group-ID are documented in "compute"_compute.html command
ke = style name of this compute command :ul

[Examples:]

compute 1 all ke :pre

[Description:]

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

The kinetic energy of each particle is computed as 1/2 m v^2, where m
and v are the mass and velocity of the particle.

There is a subtle difference between the quantity calculated by this
compute and the kinetic energy calculated by the {ke} or {etotal}
keyword used in thermodynamic output, as specified by the
"thermo_style"_thermo_style.html command.  For this compute, kinetic
energy is "translational" kinetic energy, calculated by the simple
formula above.  For thermodynamic output, the {ke} keyword infers
kinetic energy from the temperature of the system with 1/2 Kb T of
energy for each degree of freedom.  For the default temperature
computation via the "compute temp"_compute_temp.html command, these
are the same.  But different computes that calculate temperature can
subtract out different non-thermal components of velocity and/or
include different degrees of freedom (translational, rotational, etc).

[Output info:]

This compute calculates a global scalar (the summed KE).  This value
can be used by any command that uses a global scalar value from a
compute as input.  See the "Howto output"_Howto_output.html doc page
for an overview of LAMMPS output options.

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

[Restrictions:] none

[Related commands:]

"compute erotate/sphere"_compute_erotate_sphere.html

[Default:] none
