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lammps/doc/src/compute_ke.txt
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compute_ke.txt
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"LAMMPS WWW Site"_lws - "LAMMPS Documentation"_ld - "LAMMPS Commands"_lc :c
:link(lws,http://lammps.sandia.gov)
:link(ld,Manual.html)
:link(lc,Section_commands.html#comm)
: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 "Section_howto 15"_Section_howto.html#howto_15
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
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