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git-svn-id: svn://svn.icms.temple.edu/lammps-ro/trunk@10712 f3b2605a-c512-4ea7-a41b-209d697bcdaa

This commit is contained in:
sjplimp 2013-09-04 15:23:16 +00:00
parent d018e873d5
commit 06de308627
4 changed files with 32 additions and 14 deletions
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10
doc/fix_rigid.html
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@ -391,8 +391,14 @@ time units and determines how rapidly the temperature is relaxed. For
example, a value of 100.0 means to relax the temperature in a timespan
of (roughly) 100 time units (tau or fmsec or psec - see the
<A HREF = "units.html">units</A> command). The random # <I>seed</I> must be a positive
integer. The way the Langevin thermostatting operates is explained on
the <A HREF = "fix_langevin.html">fix langevin</A> doc page.
integer.
</P>
<P>The way that Langevin thermostatting operates is explained on the <A HREF = "fix_langevin.html">fix
langevin</A> doc page. If you wish to simply viscously
damp the rotational motion without thermostatting, you can set
<I>Tstart</I> and <I>Tstop</I> to 0.0, which means only the viscous drag term in
the Langevin thermostat will be applied. See the discussion on the
<A HREF = "doc/fix_viscous.html">fix viscous</A> doc page for details.
</P>
<P>IMPORTANT NOTE: When the <I>langevin</I> keyword is used with fix rigid
versus fix rigid/small, different dynamics will result for parallel

10
doc/fix_rigid.txt
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@ -377,8 +377,14 @@ time units and determines how rapidly the temperature is relaxed. For
example, a value of 100.0 means to relax the temperature in a timespan
of (roughly) 100 time units (tau or fmsec or psec - see the
"units"_units.html command). The random # {seed} must be a positive
integer. The way the Langevin thermostatting operates is explained on
the "fix langevin"_fix_langevin.html doc page.
integer.
The way that Langevin thermostatting operates is explained on the "fix
langevin"_fix_langevin.html doc page. If you wish to simply viscously
damp the rotational motion without thermostatting, you can set
{Tstart} and {Tstop} to 0.0, which means only the viscous drag term in
the Langevin thermostat will be applied. See the discussion on the
"fix viscous"_doc/fix_viscous.html doc page for details.
IMPORTANT NOTE: When the {langevin} keyword is used with fix rigid
versus fix rigid/small, different dynamics will result for parallel

13
doc/fix_viscous.html
View File

@ -76,11 +76,14 @@ needed, gamma can be adjusted for atoms of different sizes
force term to thermostat the system at a chosen temperature. The <A HREF = "fix_langevin.html">fix
langevin</A> command does this. It has the same
viscous damping term as fix viscous and adds a random force to each
atom. Hence if using fix <I>langevin</I> you do not typically need to use
fix <I>viscous</I>. Also note that the gamma of fix viscous is related to
the damping parameter of <A HREF = "fix_langevin.html">fix langevin</A>, except that
the units of gamma are force/velocity and the units of damp are time,
so that it can more easily be used as a thermostat.
atom. The random force term is proportional to the sqrt of the chosen
thermostatting temperature. Thus if you use fix langevin with a
target T = 0, its random force term is zero, and you are essentially
performing the same operation as fix viscous. Also note that the
gamma of fix viscous is related to the damping parameter of <A HREF = "fix_langevin.html">fix
langevin</A>, however the former is specified in units
of force/velocity and the latter in units of time, so that it can more
easily be used as a thermostat.
</P>
<HR>

13
doc/fix_viscous.txt
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@ -67,11 +67,14 @@ Note that Brownian dynamics models also typically include a randomized
force term to thermostat the system at a chosen temperature. The "fix
langevin"_fix_langevin.html command does this. It has the same
viscous damping term as fix viscous and adds a random force to each
atom. Hence if using fix {langevin} you do not typically need to use
fix {viscous}. Also note that the gamma of fix viscous is related to
the damping parameter of "fix langevin"_fix_langevin.html, except that
the units of gamma are force/velocity and the units of damp are time,
so that it can more easily be used as a thermostat.
atom. The random force term is proportional to the sqrt of the chosen
thermostatting temperature. Thus if you use fix langevin with a
target T = 0, its random force term is zero, and you are essentially
performing the same operation as fix viscous. Also note that the
gamma of fix viscous is related to the damping parameter of "fix
langevin"_fix_langevin.html, however the former is specified in units
of force/velocity and the latter in units of time, so that it can more
easily be used as a thermostat.
:line