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Professor Giannozzi,<div><br></div><div>Thanks a lot for your reply.</div><div><br></div><div>Elie<br><br><div>> From: giannozz@democritos.it<br>> Date: Fri, 2 Sep 2011 22:55:25 +0200<br>> To: pw_forum@pwscf.org<br>> Subject: Re: [Pw_forum] total force and number of k-points<br>> <br>> <br>> On Sep 2, 2011, at 15:54 , Elie Moujaes wrote:<br>> <br>> > I have a simple question: does the total force acting<br>> > on a system depend on the number of k-points used?<br>> <br>> not sure what you mean by "total force", but forces on<br>> atoms depend upon the number of k-points, for sure<br>> <br>> > That is in my scf calculation I am using a grid of 4x4x1<br>> > for my system whereas the grid must be denser if phonon<br>> > calculations are taking place I am using 8x8x1. Do I get<br>> > different total force acting on the system and does it mean<br>> > I have to relax the crystal twice one for an scf calculation<br>> > and another for a phonon calculation?<br>> <br>> in principle a system should be relaxed for the same set of<br>> parameters (cutoff, k-points) that are used in the subsequent<br>> phonon calculation. The difference might be small enough to<br>> be negligible, but this is something that should be checked.<br>> <br>> P.<br>> ---<br>> Paolo Giannozzi, Dept of Chemistry&Physics&Environment,<br>> Univ. Udine, via delle Scienze 208, 33100 Udine, Italy<br>> Phone +39-0432-558216, fax +39-0432-558222<br>> <br>> <br>> <br>> <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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