118 lines
4.6 KiB
Plaintext
118 lines
4.6 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
|
|
|
|
fix temp/rescale command :h3
|
|
|
|
[Syntax:]
|
|
|
|
fix ID group-ID temp/rescale N Tstart Tstop window fraction keyword values ... :pre
|
|
|
|
ID, group-ID are documented in "fix"_fix.html command
|
|
temp/rescale = style name of this fix command
|
|
N = perform rescaling every N steps
|
|
Tstart,Tstop = desired temperature at start/end of run (temperature units)
|
|
window = only rescale if temperature is outside this window (temperature units)
|
|
fraction = rescale to target temperature by this fraction
|
|
zero or more keyword/value pairs may be appended
|
|
keyword = {region} :ul
|
|
{region} values = region-ID of region to apply rescaling to :pre
|
|
|
|
[Examples:]
|
|
|
|
fix 3 flow temp/rescale 100 1.0 1.1 0.02 0.5
|
|
fix 3 boundary temp/rescale 1 1.0 1.5 0.05 1.0 region edge :pre
|
|
|
|
[Description:]
|
|
|
|
Reset the temperature of a group of atoms by explicitly rescaling
|
|
their velocities.
|
|
|
|
Rescaling is performed every N timesteps. The target temperature is a
|
|
ramped value between the {Tstart} and {Tstop} temperatures at the
|
|
beginning and end of the run.
|
|
|
|
Rescaling is only performed if the difference between the current and
|
|
desired temperatures is greater than the {window} value. The amount
|
|
of rescaling that is applied is a {fraction} (from 0.0 to 1.0) of the
|
|
difference between the actual and desired temperature. E.g. if
|
|
{fraction} = 1.0, the temperature is reset to exactly the desired
|
|
value.
|
|
|
|
The keyword {region} applies the fix only to atoms that are in the
|
|
specified geometric region (and in the fix group). Since atoms can
|
|
enter/leave a region, this test is performed each timestep.
|
|
|
|
A temp/rescale fix does not update the coordinates of its atoms. It
|
|
is normally used with a fix of style {nve} that does that. A
|
|
temp/rescale fix should not normally be used on atoms that also have
|
|
their temperature controlled by another fix - e.g. a
|
|
"nvt"_fix_nvt.html or "langevin"_fix_langevin.html fix.
|
|
|
|
This fix computes a temperature each timestep. To do this, the fix
|
|
creates its own compute of style "temp" or "temp/region", as if one of
|
|
these commands had been issued:
|
|
|
|
compute fix-ID_temp group-ID temp
|
|
compute fix-ID_temp group-ID temp/region region-ID :pre
|
|
|
|
Which is used depends on whether a region was specified with the fix.
|
|
See the "compute temp"_compute_temp.html and "compute
|
|
temp/region"_compute_temp_region.html commands for details. Note that
|
|
the ID of the new compute is the fix-ID with underscore + "temp"
|
|
appended and the group for the new compute is the same as the fix
|
|
group.
|
|
|
|
Note that this is NOT the compute used by thermodynamic output (see
|
|
the "thermo_style"_thermo_style.html command) with ID = {thermo_temp}.
|
|
This means you can change the attributes of this fix's temperature
|
|
(e.g. its degrees-of-freedom) via the
|
|
"compute_modify"_compute_modify.html command or print this temperature
|
|
during thermodyanmic output via the "thermo_style
|
|
custom"_thermo_style.html command using the appropriate compute-ID.
|
|
It also means that changing attributes of {thermo_temp} will have no
|
|
effect on this fix.
|
|
|
|
[Restart, fix_modify, thermo output, run start/stop, minimize info:]
|
|
|
|
No information about this fix is written to "binary restart
|
|
files"_restart.html.
|
|
|
|
The "fix_modify"_fix_modify.html {temp} option is supported by this
|
|
fix. You can use it to assign a "compute"_compute.html you have
|
|
defined to this fix which will be used in its thermostatting
|
|
procedure. For consistency, if using the keyword {region}, the
|
|
compute you assign should also be of style
|
|
"temp/region"_compute_temp_region.html.
|
|
|
|
The "fix_modify"_fix_modify.html {energy} option is supported by this
|
|
fix to add the energy change implied by a velocity rescaling to the
|
|
system's potential energy as part of "thermodynamic
|
|
output"_thermo_style.html. Note that because this fix is invoked
|
|
every N steps and thermodynamic info is printed every M steps, that
|
|
unless M is a multiple of N, the energy contribution will not be for
|
|
the current timestep.
|
|
|
|
The energy change can be printed as part of thermodynamic output via
|
|
the keyword f_ID, where ID is the fix-ID of this fix. See the
|
|
"thermo_style custom"_thermo_style.html command for details.
|
|
|
|
This fix can ramp its target temperature over multiple runs, using the
|
|
{start} and {stop} keywords of the "run"_run.html command. See the
|
|
"run"_run.html command for details of how to do this.
|
|
|
|
This fix is not invoked during "energy minimization"_minimize.html.
|
|
|
|
[Restrictions:] none
|
|
|
|
[Related commands:]
|
|
|
|
"fix langevin"_fix_langevin.html, "fix nvt"_fix_nvt.html,
|
|
"fix_modify"_fix_modify.html
|
|
|
|
[Default:] none
|