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Thanks for your reply. Any reference to the finite displacement method for phonon calculations using QE?<div><br></div><div><br></div><div>Thanks again</div><div><br></div><div>Elie<br><br><div><div id="SkyDrivePlaceholder"></div>> To: pw_forum@pwscf.org<br>> Date: Mon, 13 Feb 2012 16:41:04 +0100<br>> From: Lorenzo.Paulatto@impmc.upmc.fr<br>> Subject: Re: [Pw_forum] phonon calculations in a spercell of 100 atoms<br>> <br>> On Mon, 13 Feb 2012 16:36:55 +0100, Elie M <elie.moujaes@hotmail.co.uk> <br>> wrote:<br>> > Dear all,<br>> > I have two questions:<br>> > (1) I am running phonon calculations on a system of 100 atoms and only <br>> > at the Gamma point! It is really taking a lot of time. It is running in <br>> > the parallel computing mode with a total of 16 processors on 2 nodes and <br>> > still is going slow. Is there a way to speed up things? and is there a <br>> > way to do the whole phonon dispersion in lesser time?<br>> <br>> Do not use a supercell? Seriously, phonon calculations are expensive, with <br>> many atoms they are extremely expensive. If you only need the phonons at <br>> the gamma point, it may be faster to get them by finite displacement, <br>> doing 3*nat pw.x ground state calculations.<br>> <br>> > (2) If only the phonon frequencies at the Gamma point were calculated , <br>> > I was wondering what kind of information about the system can one get?<br>> > Thanks<br>> <br>> If the supercell is large enough, all the information you need.<br>> <br>> bests<br>> <br>> <br>> -- <br>> Lorenzo Paulatto IdR @ IMPMC/CNRS & Université Paris 6<br>> phone: +33 (0)1 44275 084 / skype: paulatz<br>> www: http://www-int.impmc.upmc.fr/~paulatto/<br>> mail: 23-24/4é16 Boîte courrier 115, 4 place Jussieu 75252 Paris Cédex 05<br>> _______________________________________________<br>> Pw_forum mailing list<br>> Pw_forum@pwscf.org<br>> http://www.democritos.it/mailman/listinfo/pw_forum<br></div></div> </div></body>
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