Hi Lammps users,
I am stuck with momentum artifact while temperature thermostatting.
The problem arises only while doing simulations of two temperature species
(two thermostats for two groups) in system with similar masses.
If the mass for both species are distinct, the artifact is not there. I checked with 4 different possible temperature thermostatting ways available with lammps.
While for Nose-Hoover, Berensden and Gaussian thermostats, the problem persists with similar masses and get removed if quite distinct mass ratio for both species.
For, Langevin thermostat, the problem never arises.
I tried to remove the artifact using “fix momentum” but the issue persists. It seems that artifact is arising in as less as 2000 time steps (following the velocity distribution in time).
Also, rescale option used as following command is giving error.
fix mm1 all momentum 1 linear 1 1 1 rescale
I will appreciate is some of you can give suggestions about possible lammps options to get rid of this artifact.
Thanks,
Hi Lammps users,
I am stuck with momentum artifact while temperature thermostatting.
The problem arises only while doing simulations of two temperature species
(two thermostats for two groups) in system with similar masses.
If the mass for both species are distinct, the artifact is not there. I
checked with 4 different possible temperature thermostatting ways available
with lammps.
While for Nose-Hoover, Berensden and Gaussian thermostats, the problem
persists with similar masses and get removed if quite distinct mass ratio
for both species.
For, Langevin thermostat, the problem never arises.
I tried to remove the artifact using "fix momentum" but the issue
persists. It seems that artifact is arising in as less as 2000 time steps
(following the velocity distribution in time).
that means that this is not automatically an artifact of the thermostat,
but more likely an artifact of your simulation setup. there are tons of
things that can have an impact and it is impossible to provide good advice
on vague descriptions. if you provide a small, simple, easy to follow input
deck that reproduces the problem, people may be able to look into it, but
not based on the info provided so far. the fact that fix momentum doesn't
remove the C.O.M. drift is confirmation, that this has to be systemic.
Also, rescale option used as following command is giving error.
fix mm1 all momentum 1 linear 1 1 1 *rescale*
which likely means, that you are using a older version of LAMMPS, that
does not support this feature.
I will appreciate is some of you can give suggestions about possible
lammps options to get rid of this artifact.
i am rather confident, that this is not so much a LAMMPS problem, but
rather caused by the design of the model
axel.