[Thermo_pw-forum] Gratitude

[Andrea Dal Corso]

On Thu, 2016-08-11 at 22:39 +0100, Abolore Musari wrote:
> Sir,
> I want to appreciate the admin for approving my request to be part of this
> forum.. May God continue to enrich u with lots of wisdom and knowledge.
> Sir, I must confess thermo_pw package is a wonderful code and i just
> started using it recently to calculate phonon dispersion and thermodynamic
> properties using scf_disp aand its been of great help but Sir, I will like
> to ask that for an unstable system with negative frequencies the code is
> giving me an output for Entropy and vibrational free energy which l could
> not obtain normally using quasiharmonic approximation which always return

Thermo_pw is tollerant with a few negative frequencies and computes the
vibrational energy and free energy disregarding them. It is
responsibility of the user to check that he has no negative frequencies
in his dispersions and to judge if to trust the computed vibrational
energy and free energy.

HTH,
Andrea


> NaN for the Entropy and vibrational free energy   and am wondering if it is
> right to get values for this knowing that its an unstable system and if it
> is right how can it be obtained with quasiharmonic approximation code in QE.
> 
> Thanks
> Musari A.A
> Department of Physics
> Federal University of Agriculture, Abeokuta
> Nigeria
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Andrea Dal Corso                    Tel. 0039-040-3787428
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