I am cooling my sytem from 3000K to 0K, using the following commands (metal units):
fix 1 coreatoms langevin 3000 0.0 0.06 48279
fix 2 coreatoms nve
and run for about 20 ps (0.1 fs timestep). I would need 2 clarifications about this procedure:
By the end of my run, the temperature is not exactly 0K, but around 10K. Is it just a matter of increasing the number of steps, or modifying the damping parameter? (I am currently investigating this possibility)
Also, I observed that the temperature is decreasing linearly during the run. I would have rather expected an exponential decay, driven by some tau. Is the linear decay always used with this fix command? And/or is there a way to modify the way this is done?
Thanks a lot