lammps/doc/compute_ke.txt

62 lines
1.9 KiB
Plaintext

"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 or 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 KE). This value can be
used by any command that uses a global scalar value from a compute as
input. See "this section"_Section_howto.html#4_15 for an overview of
LAMMPS output options.
The scalar value calculated by this compute is "extensive", meaning it
it scales with the number of atoms in the simulation.
The scalar value will be in energy "units"_units.html.
[Restrictions:] none
[Related commands:]
"compute erotate/sphere"_compute_erotate_sphere.html
[Default:] none