[Pw_forum] Phonons of molecular crystal

[Guntram Schmidt]

Dear Stefano,

do you think it is appropiate to use another functional to calculate the 
phonon spectra of molecular crystals? I just want to have some rough 
approximation of an IR spectrum and maybe get QHA total energies?

Thanks,
Guntram


Am 01.09.2011 12:37, schrieb Stefano de Gironcoli:
> Dear Guntram,
>       be careful that vdW-DF functional IS NOT yet implemented in the
> phonon  code
> Stefano
>
> On 09/01/2011 12:23 PM, Guntram Schmidt wrote:
>> Dear All,
>>
>> I want to simulate the infrared spectrum of a molecular crystal.
>> As the phonon calculations usually take weeks to finish, I'd like to
>> ask, wether someone of you has propositions on proper treshold values?
>>
>> I'm using rpb-paw US pseudopotential (revised PBE, as suggested for
>> vdW-potential) and gamma point (also said to be sufficient for molecular
>> crystals).
>>
>> Does the ecutrho of the preceding SCF calculation influence the speed of
>> the phonon calculation?
>>
>> What is a sufficient low value for the tr2_ph to get a reasonable
>> (comparable to experimental values) spectrum?
>>
>>
>> Thanks a lot,
>> Guntram
>> _______________________________________________
>> Pw_forum mailing list
>> Pw_forum at pwscf.org
>> http://www.democritos.it/mailman/listinfo/pw_forum
>
> _______________________________________________
> Pw_forum mailing list
> Pw_forum at pwscf.org
> http://www.democritos.it/mailman/listinfo/pw_forum