if the slab is a solid, I think you may obtain an oscillating MSD (with maximum amplitude less than sigma^2)
even if the system is equilibrated. May be if you run it for a very long time, you end up smoothing the oscillations
to an almost constant very small value, but I would not consider one or the other as an indication that the system
is or not in equilibrium.
If msd oscillates with an amplitude that is bigger than sigma^2, that may be an indication of something wrong and
I do not know what it may be.
Dear Lammps users,
I'm having trouble obtaining equilibrium on my system. I've been trying to
follow several papers that deal with a slab of metallic atoms in the way
equilibrium at a certain temperature is achieved but they don't seem to work
in lammps for the bulk (periodic boundary conditions) or a free surface.
I've noticed that even though the velocities oscillate slowly at a given
temperature the msd seems to oscillate a lot.
I'm trying two schemes:
1. setting the temperature of the system at 0 K using velocity create and
then very slowly (in 200 ps increasing the temperature in 25 K intervals)
using temp/rescale. Doing velocity rescaling for 20 ps using temp/rescale to
make sure that the system oscillates around a certain temperature, and then
a 50 ps run without constraints using time integration according to the
microcanonical ensemble (at this point I unfix the temp/rescale command).
2. setting the temperature of the system at the desired temperature (instead
of 0 K) and then repeating the same procedure as 1.
lammps-users mailing list
Materials and Process Simulation Center [email protected]
139-74 Beckman Institute Phone: +1-626-395 2724
California Institute of Technology Fax: +1-626-585 0918
Pasadena, California 91125, U.S.A.