[CPMD-list] printing out the fictitious velocities for CPMD simulations

[Juerg Hutter]

Hi

I suggest that you use a more pragmatic approach.
Start from an electron mass used in a good simulation
of a similar system as yours reported in the litterature.
If you want you can increase this value slightly and
run test jobs on a (smaller) test system to see if it
still behaves nicely.

regards

Juerg Hutter

----------------------------------------------------------
Juerg Hutter                   Phone : ++41 44 635 4491
Physical Chemistry Institute   FAX   : ++41 44 635 6838
University of Zurich           E-mail: hutter at pci.unizh.ch
Winterthurerstrasse 190
CH-8057 Zurich, Switzerland
----------------------------------------------------------


On Wed, 29 Nov 2006, Hakan Gunaydin wrote:

> Dear CPMD users,
>
> I am interested in running CPMD simulations. My problem is with the
> fictitious mass. I would like to be able to determine what is the upper
> limit of the fictitious mass that I can use for any given system and still
> conserve the adiabaticity of the ionic - electronic separation.
>
> As far as I know, the way to check the adiabatic separation between the
> ionic motion and electronic motion is to compare the power
> spectrum of the wavefunction due to fictitious mass to the power spectrum
> of the sytem itself. As long as the highest frequency of the actual system
> is well separated from the lowest electronic frequency, I can use the
> given fictitious mass.
>
> My question is, is there a way to print out the fictitious velocities for
> the motion of the wavefunction for CPMD simulations? If I know what the
> velocities are, I can use the Fourier transform of the velocity
> autocorrelation function to get the electronic power specturum. Or is
> there an alternative (more trivial) approch to find the upper limit for
> the fictitious mass?
>
> Best Regards,
> -Hakan
> _______________________________________________
> CPMD-list mailing list
> CPMD-list at cpmd.org
> http://cpmd.org/mailman/listinfo/cpmd-list
>