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git-svn-id: svn://svn.icms.temple.edu/lammps-ro/trunk@4649 f3b2605a-c512-4ea7-a41b-209d697bcdaa

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sjplimp
2010-09-01 19:53:20 +00:00
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40
doc/fix_temp_rescale.txt
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@ -6,14 +6,14 @@
:line
fix temp/rescale command :h3
fix temp/rescale/eff command :h3
[Syntax:]
fix ID group-ID temp/rescale N Tstart Tstop window fraction :pre
fix ID group-ID temp/rescale/eff N Tstart Tstop window fraction :pre
ID, group-ID are documented in "fix"_fix.html command
temp/rescale = style name of this fix command
temp/rescale/eff = 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)
@ -21,21 +21,15 @@ fraction = rescale to target temperature by this fraction :ul
[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
fix 3 boundary temp/rescale 1 1.0 1.5 0.05 1.0 :pre
fix 3 flow temp/rescale/eff 10 1.0 100.0 0.02 1.0 :pre
[Description:]
Reset the temperature of a group of atoms by explicitly rescaling
their velocities.
The rescaling is applied to only the translational degrees of freedom
for the particles, which is an important consideration if extended
spherical or aspherical particles which have rotational degrees of
freedom are being thermostatted with this fix. The translational
degrees of freedom can also have a bias velocity removed from them
before thermostatting takes place; see the description below.
The rescaling is applied to the translational degrees of freedom
for all particles, and the electronic radial degrees of freedom. The translational degrees of freedom can also have a bias velocity removed from them before thermostatting takes place; see the description below.
Rescaling is performed every N timesteps. The target temperature is a
ramped value between the {Tstart} and {Tstop} temperatures at the
@ -48,15 +42,14 @@ difference between the actual and desired temperature. E.g. if
{fraction} = 1.0, the temperature is reset to exactly the desired
value.
IMPORTANT NOTE: Unlike the "fix nvt"_fix_nh.html command which
IMPORTANT NOTE: Unlike the "fix nvt/eff"_fix_nh.html command which
performs Nose/Hoover thermostatting AND time integration, this fix
does NOT perform time integration. It only modifies velocities to
effect thermostatting. Thus you must use a separate time integration
fix, like "fix nve"_fix_nve.html to actually update the positions of
atoms using the modified velocities. Likewise, this fix should not
fix, like "fix nve/eff"_fix_nve_eff.html to actually update the positions of atoms using the modified velocities. Likewise, this fix should not
normally be used on atoms that also have their temperature controlled
by another fix - e.g. by "fix nvt"_fix_nh.html or "fix
langevin"_fix_langevin.html commands.
by another fix - e.g. by "fix nvt/eff"_fix_nh.html or "fix
langevin/eff"_fix_langevin_eff.html commands.
See "this howto section"_Section_howto.html#4_16 of the manual for a
discussion of different ways to compute temperature and perform
@ -66,10 +59,9 @@ This fix computes a temperature each timestep. To do this, the fix
creates its own compute of style "temp", as if one of this command had
been issued:
compute fix-ID_temp group-ID temp :pre
compute fix-ID_temp group-ID temp/eff :pre
See the "compute temp"_compute_temp.html for details. Note that the
ID of the new compute is the fix-ID + underscore + "temp", and the
See the "compute temp/eff"_compute_temp_eff.html for details. Note that the ID of the new compute is the fix-ID + underscore + "temp", 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
@ -124,11 +116,15 @@ This fix can ramp its target temperature over multiple runs, using the
This fix is not invoked during "energy minimization"_minimize.html.
[Restrictions:] none
[Restrictions:]
This fix is part of the "user-eff" package. It is only enabled if
LAMMPS was built with that package. See the "Making
LAMMPS"_Section_start.html#2_3 section for more info.
[Related commands:]
"fix langevin"_fix_langevin.html, "fix nvt"_fix_nh.html,
"fix langevin/eff"_fix_langevin.html, "fix nvt/eff"_fix_nh.html,
"fix_modify"_fix_modify.html
[Default:] none