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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
keyword = {region} or {partial} :ul
  {region} values = region-ID
    region-ID = ID of region to apply rescaling to
  {partial} values = xflag yflag zflag
    xflag,yflag,zflag = 0/1 if the velocity component should not or should be rescaled :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
fix 3 boundary temp/rescale 1 1.0 1.5 0.05 1.0 partial 0 1 1 :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.

The keyword {partial} rescales only the specified velocity components.
A compute of style temp/partial is used to compute the current
temperature of just those components (see below).

The {region} and {partial} keywords cannot currently be used together.

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" or
"temp/partial", 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 
compute fix-ID_temp group-ID temp/partial xflag yflag zflag :pre

Which is used depends on whether the {region} or {partial} keywords
were specified with the fix.  See the "compute
temp"_compute_temp.html, "compute
temp/region"_compute_temp_region.html, and "compute
temp/partial"_compute_temp_partial.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, 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 be zero.

The potential energy change due to this fix is stored as a scalar
quantity, which can be accessed by various "output
commands"_Section_howto.html#4_15.

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
