lammps/doc/fix_temp_rescale.txt

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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 to the args
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.  The "run"_run.html command documents
how to make the ramping take place across multiple runs.

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 "_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.  Alternatively, you can directly assign a new
compute (for calculating temeperature) that you have defined to this
fix via the "fix_modify"_fix_modify.html command.  For consistency, if
using the keyword {region}, the compute you assign should also be of
style {temp/region}.

This fix makes a contribution to the potential energy of the system
that can be included in thermodynamic output of potential energy using
the "fix_modify energy"_fix_modify.html option.  The contribution can
also be printed by itself via the keyword {f_fix-ID} in the
"thermo_style custom"_thermo_style.html command.  Note that because
this fix is invoked every N steps and thermodynamic info may be
printed every M steps, that unless M is a multiple of N, the energy
info accessed will not be for the current timestep.

[Restrictions:] none

[Related commands:]

"fix langevin"_fix_langevin.html, "fix nvt"_fix_nvt.html,
"fix_modify"_fix_modify.html

[Default:] none