[Pw_forum] error in phonon calculation

Paolo Giannozzi giannozz at nest.sns.it
Wed Nov 17 18:24:36 CET 2004

On Wednesday 17 November 2004 13:34, Jose C. Conesa wrote:

> Concerning the answers by Stefano, Paolo and Eyvaz to my question:
> From Stefano:
> > The message you mention should come out when performing a calculation
> > with lsda flag on and fixed occupation . is this your situation ?
> No. The system is indeed spin-polarized (nspin = 2,
> starting_magnetization(1) = 1) and uses lda, but I have
> "occupations = 'tetrahedra' "

are you sure? Phonon calculation in metals with the tetrahedron
method is not implemented: the code stops immediately if you try.
Only smearing is implemented.

> From Paolo:
> >actually this message shows up also in a spin-polarized calculation
> > with free occupations but no smearing or tetrahedron technique.
> > This case used to be forbidden in the self-consistent calculation,
> > but I think it is allowed now, so the message might be obsolete.
> Well, then: should I disregard the message, and rely on the calculation
> (from this point of view) after all?

I am not sure, but it seems to me that in a spin-polarized system the 
number of occupied bands might be incorrectly computed by the
phonon code in that particular case

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Paolo Giannozzi             e-mail:  giannozz at nest.sns.it
Scuola Normale Superiore    Phone:   +39/050-509876, Fax:-563513 
Piazza dei Cavalieri 7      I-56126 Pisa, Italy

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