Dear Dr. Paulatto, Thanks for your reply. However:
a) I still do not understand why this subroutine is necessary. b) "if a point q is on the border of the WS cell, it finds the number N of translationally equivalent point q+G (where G is a lattice vector) that are also on the border of the cell. Than, weight = 1/N". What I do not understand from the above mentioned statement is, in this wsweight subroutine, the expanded Wigner-Seitz cell is constructed in the REAL space keeping in mind a finite no. of nearest neighbors. The weights are subsequently calculated based on the distance between the atoms. If that is the case, how does the concept of q-point fit here, since q-points belong to the RECIPROCAL space. c) Is it possible to obtain Fourier interpolation of dynamical matrices without the use of wsweight? I would really appreciate if you could shed some light on these issues. Many thanks once again! :-) Cheers, Aaditya 5. Question on the wsweight subroutine (Aaditya Manjanath) > 6. Re: Question on the wsweight subroutine (Lorenzo Paulatto) > > > > Message: 5 > Date: Fri, 29 Mar 2013 21:57:33 +0530 > From: Aaditya Manjanath <aadipotter at gmail.com> > Subject: [Pw_forum] Question on the wsweight subroutine > To: pw_forum at pwscf.org > Message-ID: > < > CALcVMZKdB5iKjujb6nsNC2bT215UeZcOmuStB-6NdfXqKejnpg at mail.gmail.com> > Content-Type: text/plain; charset="iso-8859-1" > > Dear all, > > I was looking through the matdyn program wherein the dynamical matrices are > calculated at any q-point through Fourier interpolation and I came across > the wsweight subroutine. > > I know that this subroutine calculates the weight factors that are used in > the Fourier interpolation formula.I tried calculating the dynamical matrix > at a point (0 0.6667 0, say) without using the weight factors and > interestingly, I found that the values of the dynamical matrix obtained > through matdyn do not match with those calculated directly. > > I would like to know, what is the purpose/logic of this subroutine, since I > see that this is an essential part in calculating the dynamical matrices at > arbitrary q-points. > > I would be grateful if you could shed some light on this problem. > > Cheers, > > Aaditya > > -- > "Stay hungry. Stay Foolish" - Steve Jobs > > Om Sri Sairam > Best Regards, > Aaditya Manjanath > PhD Engineering Programme > Interdisciplinary Program - Nanoscience and Engineering > Indian Institute of Science > Bangalore - 560012 > > Webpage - http://mrc.iisc.ernet.in/~abhishek/Aaditya.html > Email ID - aadipotter at gmail.com, aaditya.m at cense.iisc.ernet.in > Skype - aadipotter > -------------- next part -------------- > An HTML attachment was scrubbed... > URL: > http://pwscf.org/pipermail/pw_forum/attachments/20130329/2016c83b/attachment-0001.html > > ------------------------------ > > Message: 6 > Date: Fri, 29 Mar 2013 17:52:45 +0100 > From: Lorenzo Paulatto <lorenzo.paulatto at impmc.upmc.fr> > Subject: Re: [Pw_forum] Question on the wsweight subroutine > To: PWSCF Forum <pw_forum at pwscf.org> > Message-ID: <5155C6DD.4090807 at impmc.upmc.fr> > Content-Type: text/plain; charset="iso-8859-1" > > On 03/29/2013 05:27 PM, Aaditya Manjanath wrote: > I would like to know, what is the purpose/logic of this subroutine, > since I see that this is an essential part in calculating the dynamical > matrices at arbitrary q-points. > > > > I would be grateful if you could shed some light on this problem. > > Dear Aaditya, > wsweights does a very simple task in a very complicated way. It assigns > this weights: > 1) if a point is inside the Wigner-Seitz cell: weight=1 > 2) if a point is outside the WS cell: weight=0 > 3) if a point q is on the border of the WS cell, it finds the number N > of translationally equivalent point q+G (where G is a lattice vector) > that are also on the border of the cell. Than, weight = 1/N > > I.e. if a point is on the surface of the WS cell of a cubic lattice > it'll have weight 1/2, on the vertex of the WS it would be 1/8; the K > point of an hexagonal lattice has weight 1/3 and so on. > > It takes some thought and some time to understand wsweight; if I > remember correctly, Schwarz inequality is used < > http://en.wikipedia.org/wiki/Cauchy%E2%80%93Schwarz_inequality> > <http://en.wikipedia.org/wiki/Cauchy%E2%80%93Schwarz_inequality> > > bests > > > -- > Dr. Lorenzo Paulatto > IdR @ IMPMC -- CNRS & Universit? Paris 6 > phone: +33 (0)1 44275 084 / skype: paulatz > www: http://www-int.impmc.upmc.fr/~paulatto/ > mail: 23-24/4?16 Bo?te courrier 115, 4 place Jussieu 75252 Paris C?dex 05 > > -------------- next part -------------- > An HTML attachment was scrubbed... > URL: > http://pwscf.org/pipermail/pw_forum/attachments/20130329/bfa70159/attachment-0001.html > -- "Stay hungry. Stay Foolish" - Steve Jobs Om Sri Sairam Best Regards, Aaditya Manjanath PhD Engineering Programme Interdisciplinary Program - Nanoscience and Engineering Indian Institute of Science Bangalore - 560012 Webpage - http://mrc.iisc.ernet.in/~abhishek/Aaditya.html Email ID - aadipotter at gmail.com, aaditya.m at cense.iisc.ernet.in Skype - aadipotter -------------- next part -------------- An HTML attachment was scrubbed... URL: http://pwscf.org/pipermail/pw_forum/attachments/20130420/34cd3aab/attachment.html
