"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/partial command :h3

[Syntax:]

compute ID group-ID temp/partial xflag yflag zflag :pre

ID, group-ID are documented in "compute"_compute.html command
temp/partial = style name of this compute command
xflag,yflag,zflag = 0/1 for whether to exclude/include this dimension :ul

[Examples:]

compute newT flow temp/partial 1 1 0 :pre

[Description:]

Define a compute to calculate the temperature of a group of atoms,
after excluding one or more velocity components.  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, "fix npt"_fix_npt.html, etc.

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 = dimensionality of the simulation, N = number of atoms in the
group, k = Boltzmann constant, and T = temperature.  The calculation
of KE excludes the x, y, or z dimensions if xflag, yflag, or zflag =
0.  The dim parameter is adjusted to give the correct number of
degrees of freedom.

A 6-component kinetic energy tensor is also calculated by this compute
for use in the calculation 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 assumed to be
constant for the duration of the run; use the {dynamic} option of the
"compute_modify"_compute_modify.html command if this is not the case.

This compute subtracts out degrees-of-freedom due to fixes that
constrain molecular motion, such as "fix shake"_fix_shake.html and
"fix rigid"_fix_rigid.html.  This means the temperature of groups of
atoms that include these constraints will be computed correctly.  If
needed, the subtracted degrees-of-freedom can be altered using the
{extra} option of the "compute_modify"_compute_modify.html command.

[Output info:]

The scalar value calculated by this compute is "intensive", meaning it
is independent of the number of atoms in the simulation.  The vector
values are "extensive", meaning they scale with the number of atoms in
the simulation.

[Restrictions:] none

[Related commands:]

"compute temp"_compute_temp.html, "compute
temp/region"_compute_temp_region.html, "compute
pressure"_compute_pressure.html

[Default:] none