[Pw_forum] phonon calculations in a spercell of 100 atoms

[Elie M]

Thanks for your reply. Any reference to the finite displacement method for phonon calculations using QE?

Thanks again
Elie

> To: pw_forum at pwscf.org
> Date: Mon, 13 Feb 2012 16:41:04 +0100
> From: Lorenzo.Paulatto at impmc.upmc.fr
> Subject: Re: [Pw_forum] phonon calculations in a spercell of 100 atoms
> 
> On Mon, 13 Feb 2012 16:36:55 +0100, Elie M <elie.moujaes at hotmail.co.uk>  
> wrote:
> > Dear all,
> > I have two questions:
> > (1) I am running phonon calculations on a system of 100 atoms  and only  
> > at the Gamma point!  It is really taking a lot of time. It is running in  
> > the parallel computing mode with a total of 16 processors on 2 nodes and  
> > still is going slow. Is there a way to speed up things? and is there a  
> > way to do the whole phonon dispersion in lesser time?
> 
> Do not use a supercell? Seriously, phonon calculations are expensive, with  
> many atoms they are extremely expensive. If you only need the phonons at  
> the gamma point, it may be faster to get them by finite displacement,  
> doing 3*nat pw.x ground state calculations.
> 
> > (2) If only the phonon  frequencies at the Gamma point were calculated ,  
> > I was wondering what kind of information about the system can one get?
> > Thanks
> 
> If the supercell is large enough, all the information you need.
> 
> bests
> 
> 
> -- 
> Lorenzo Paulatto IdR @ IMPMC/CNRS & Université Paris 6
> phone: +33 (0)1 44275 084 / skype: paulatz
> www:   http://www-int.impmc.upmc.fr/~paulatto/
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