On 02/08/2014 12:00 PM, pw_forum-request at pwscf.org wrote: > Message: 2 Date: Fri, 07 Feb 2014 16:25:14 +0100 From: Paolo Giannozzi > <paolo.giannozzi at uniud.it> Subject: Re: [Pw_forum] Error in routine > sym_rho_init_shell "lone vector" with fixed FFT dimension To: PWSCF > Forum <pw_forum at pwscf.org> Message-ID: > <1391786714.5521.99.camel at fe12lx.fisica.uniud.it> Content-Type: > text/plain; charset="UTF-8" On Thu, 2014-02-06 at 12:58 +0100, Thomas > Gruber wrote: >> > I attached 2 inputs files. One with smaller volume works and one with >> > greater volume with the corresponding *.out file, which works not. Since >> > I have already done phonon calculations for 5 different volumes, I don't >> > want to change the FFT dimension. I fixed it to 48 48 200 and the not >> > fixed FFT dimension would be 50 50 200. >> > Any suggestions? > it works if you reduce by a little bit "ecutrho" from its default value > 4*ecutwfc. The problem is that if you keep the FFT grid fixed, you may > "miss" a few G-vectors. The algorithm that divides G-vectors into shells > of vectors transforming into each other cannot work if a shell is > incomplete. Alternatively: remove symmetry, since such algorithm is > used only for symmetrization of the charge density. I have no better > ideas right now: finding an algorithm that is guaranteed to work if > the FFT grid is not sufficient to accommodate the G-vector sphere > up to G^2< ecutrho may require a serious effort > > Paolo > Thanks, that works. If I change the "ecutrho" value than I don't have to fix the FFT dimension. I fixed the FFT dimension to keep the energies for all volumes for a QHA calculation comparable and to not get energy jumps. Would that work if I just reduce the ecutrho in that amount to keep the G-vectors constant? For my case I would have to decrease the "ecutrho" from 320 to 290 by 5% volume increase.
Best regards, Thomas Gruber -- TU Bergakademie Freiberg Dipl. Chem. Thomas Gruber Institut f?r Theoretische Physik Leipziger Str. 23 / OG. 14 D-09599 Freiberg Tel: +49 3731 39-2006 Email:thomas.gruber at physik.tu-freiberg.de Webseite: tu-freiberg.de -------------- next part -------------- An HTML attachment was scrubbed... URL: http://pwscf.org/pipermail/pw_forum/attachments/20140226/f3dae9ae/attachment.html
