[QE-users] temperature fluctuations in NVT ensemble in Car-Parinello calculations

[Zahra Nourbakhsh]

Dear experts,

I am doing CPMD calculations for water in the NVT ensemble where the ionic
temperature is controlled using Nose-Hoover thermostat.
After several femtoseconds, the system finds its equilibrium, and the
temperature oscillates around the intended temperature. I see that using
different pseudopotentials or vdw-correction, the temperature changes
around the equilibrium are different.
I know these fluctuations come from the limited size of the system and they
will be reduced by increasing the number of molecules in the system;
however, my question is that is there any limitation on the acceptable
value for  (T_max-T_0)/T_0 or (T_0 -T_min)/T_0?  T_0 is the considered
temperature.
And is there any parameter or any way to reduce these fluctuations?

I am almost beginner in MD calculations and would be very happy to find
your idea.

Yours sincerely,
Zahra Nourbakhsh
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.quantum-espresso.org/pipermail/users/attachments/20200519/1eaf7c69/attachment.html>