"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 temp/region command :h3

[Syntax:]

compute ID group-ID temp/region region-ID :pre

ID, group-ID are documented in "compute"_compute.html command
temp/region = style name of this compute command
region-ID = ID of region to use for choosing atoms :ul

[Examples:]

temperature mine flow region boundary :pre

[Description:]

Define a computation that calculates the temperature of a group of
atoms in a geometric region.  This can be useful for thermostatting
one portion of the simulation box.  E.g. a McDLT simulation where one
side is cooled, and the other side is heated.  A compute of this style
can be used by any command that computes a temperature,
e.g. "thermo_modify"_thermo_modify.html, "fix
temp/rescale"_fix_temp_rescale.html, etc.

Note that a {region}-style temperature can be used to thermostat with
"fix temp/rescale"_fix_temp_rescale.html or "fix
langevin"_fix_langevin.html, but should probably not be used with
Nose/Hoover style fixes ("fix nvt"_fix_nvt.html, "fix
npt"_fix_npt.html, or "fix nph"_fix_nph.html), if the
degrees-of-freedom included in the computed T varies with time.

The temperature is calculated by the formula KE = dim/2 N k T, where
KE = total kinetic energy of the group of atoms (sum of 1/2 m v^2),
dim = 2 or 3 = dimensionality of the simulation, N = number of atoms
in both the group and region, k = Boltzmann constant, and T =
temperature.

A 6-component kinetic energy tensor is also calculated by this compute
for use in the computation of a pressure tensor.  The formula for the
components of the tensor is the same as the above formula, except that
v^2 is replaced by vx * vy for the xy component, etc.

The number of atoms contributing to the temperature is compute each
time the temperature is evaluated since it is assumed atoms can
enter/leave the region.  Thus there is no need to use the {dynamic}
option of the "compute_modify"_compute_modify.html command for this
compute style.

Unlike other compute styles that calculate temperature, this compute
does NOT currently subtract out degrees-of-freedom due to fixes that
constrain molecular motion, such as "fix shake"_fix_shake.html and
"fix rigid"_fix_rigid.html.  If needed the subtracted
degrees-of-freedom can be altered using the {extra} option of the
"compute_modify"_compute_modify.html command.

[Restrictions:] none

[Related commands:]

"compute temp"_compute_temp.html, "compute
pressure"_compute_pressure.html

[Default:] none
