[Pw_forum] temperature rescaling for vc-md

Giovanni La Penna glapenna at iccom.cnr.it
Mon Feb 28 10:31:49 CET 2011

I would suggest to heat the system slowly.
means that previous velocities are not loaded.
So going from zero (for a hopefully relaxed system) to 300 K,
with a time-step of 1 fs (if a remember correctly), may imply
a huge time to converge at each time step.
Even CP would not work properly this way: it runs, but temperature
oscillations become huge and the fake electron
kinetic energy would quickly increase, providing
an uncontrolled dynamics.
Other codes may have hidden controls on temperature,
time-steps, etc..


Giovanni La Penna - National research council (Cnr)
Institute for chemistry of organo-metallic compounds (Iccom)
via Madonna del Piano 10,
I-50019 Sesto Fiorentino, Firenze, Italy
tel.: +39 055 522-5264, fax: +39 055 522-5203
e-mail: glapenna at iccom.cnr.it - http://www.iccom.cnr.it/lapenna
skype: giovannilapenna

On Mon, 28 Feb 2011, Huiqun Zhou wrote:

> ...
> but the SCF convergence is always failed to reach after 20 or so ion steps
> no matter
> how I change mixing_beta from 0.5 to 0.05. One thing I noticed is that the
> temperature
> controling may be not in effect as the temperature remains as high as 6
> digits. I used
> ...

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