git-svn-id: svn://svn.icms.temple.edu/lammps-ro/trunk@2933 f3b2605a-c512-4ea7-a41b-209d697bcdaa

This commit is contained in:
sjplimp 2009-06-30 22:51:36 +00:00
parent 87c330d436
commit b58c43a5ec
2 changed files with 14 additions and 4 deletions

View File

@ -57,6 +57,11 @@ optional keyword <I>scale</I> is used, gamma can scaled up or down by the
specified factor for atoms of that type. It can be used multiple
times to adjust gamma for several atom types.
</P>
<P>IMPORTANT NOTE: You should specify gamma in force/velocity units.
This is not the same as mass/time units, at least for some of the
LAMMPS <A HREF = "units.html">units</A> options like "real" or "metal" that are not
self-consistent.
</P>
<P>In a Brownian dynamics context, gamma = kT / D, where k = Boltzmann's
constant, T = temperature, and D = particle diffusion coefficient. D
can be written as kT / (3 pi eta d), where eta = dynamic viscosity of
@ -76,8 +81,8 @@ 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 (or mass/time) and the units of
damp are time, so that it can more easily be used as a thermostat.
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.
</P>
<P><B>Restart, fix_modify, output, run start/stop, minimize info:</B>
</P>

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@ -47,6 +47,11 @@ optional keyword {scale} is used, gamma can scaled up or down by the
specified factor for atoms of that type. It can be used multiple
times to adjust gamma for several atom types.
IMPORTANT NOTE: You should specify gamma in force/velocity units.
This is not the same as mass/time units, at least for some of the
LAMMPS "units"_units.html options like "real" or "metal" that are not
self-consistent.
In a Brownian dynamics context, gamma = kT / D, where k = Boltzmann's
constant, T = temperature, and D = particle diffusion coefficient. D
can be written as kT / (3 pi eta d), where eta = dynamic viscosity of
@ -66,8 +71,8 @@ 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 (or mass/time) and the units of
damp are time, so that it can more easily be used as a thermostat.
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.
[Restart, fix_modify, output, run start/stop, minimize info:]