[Pw_forum] phonon

[Stefano Baroni]

Unless Zahra wanted to know how to obtain phonons from the electronic  
structure calculate by sampling only the gamma point of the Brillouin  
zone (BZ). Beware that the k-points used to sample the BZ (which i  
like to call "k points") have nothing to do with the k-points at  
which phonon frequencies are calculated (which I like to call "q  
points"). If you quant to calculate phonons at q-point=gamma, then  
please follow the suggestions by Giovanni Cantele and Stefano de  
Gironcoli. Otherwise, please make sure that you understand the  
difference between "k points" and "q points" (see my sloppy  
definition above). If you don't, please revert to us before  
proceeding. Good luck - SB

On Oct 29, 2007, at 9:21 PM, Giovanni Cantele wrote:

> zahra sadat naghavi wrote:
>> what should i do if i want to calculat phonon frequencies at gama
>> point for a metal?
> perhaps it could be helpful starting browsing the code  
> documentation and
> examples:
>
> http://www.quantum-espresso.org/wiki/index.php/ 
> Using_PWscf#Phonon_calculations
>
> espresso-3.2/examples/example02
>
> example 02 shows you "how to use pw.x and ph.x to calculate phonon
> frequencies at Gamma and X for Si and C in the diamond structure and
> for fcc-Ni."
>
>
> Giovanni
>
> -- 
>
>
>
> Dr. Giovanni Cantele
> Coherentia CNR-INFM and Dipartimento di Scienze Fisiche
> Universita' di Napoli "Federico II"
> Complesso Universitario di Monte S. Angelo - Ed. 6
> Via Cintia, I-80126, Napoli, Italy
> Phone: +39 081 676910
> Fax:   +39 081 676346
> E-mail: Giovanni.Cantele at na.infn.it
> Web: http://people.na.infn.it/~cantele
>
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---
Stefano Baroni - SISSA  &  DEMOCRITOS National Simulation Center -  
Trieste
[+39] 040 3787 406 (tel) -528 (fax) / stefanobaroni (skype)

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