forked from lijiext/lammps
64 lines
2.3 KiB
Plaintext
64 lines
2.3 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 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.
|
||
|
|
|
||
|
|
[Restrictions:] none
|
||
|
|
|
||
|
|
[Related commands:]
|
||
|
|
|
||
|
|
"compute temp"_compute_temp.html, "compute
|
||
|
|
temp/region"_compute_temp_region.html, "compute
|
||
|
|
pressure"_compute_pressure.html
|
||
|
|
|
||
|
|
[Default:] none
|