Sincerely thanks to Davide for your explaination. I would hope your further
investigation.Best wishes. Ning Lu ????????????????????: >From: Davide Ceresoli <ceresoli at MIT.EDU> >Reply-To: >To: nlu at mail.ustc.edu.cn, PWSCF Forum <pw_forum at pwscf.org> >Subject: Re: [Pw_forum] Fwd:NMR of benzene >Date:Fri, 07 Aug 2009 10:49:53 -0400 > >nlu at mail.ustc.edu.cn wrote: > >> From: "" <nlu at mail.ustc.edu.cn> > >> Reply-To: "" <nlu at mail.ustc.edu.cn> > >> To: pw_forum at pwscf.org > >> Subject: NMR of benzene > >> Date:Fri, 07 Aug 2009 21:22:14 +0800 > >> > >> Dear all, > >> I have used GIPAW to calculate NMR of benzene recently. I have two > >> question, > > the > >> first is why the mass of diamond C is 12 in the input file, in the examples of > >> GIPAW, why not 13? > Dear Lu, > the NMR calculation is done at fixed atomic positions. The > mass of the isotope matters only when computing phonons. > > Notice that in the NMR calculation, every nucleus is considered > NMR active (with nuclear spin > 0). In reality, if the sample is > not enriched, one should take into account the natural abundance > of every isotope. > > >> The second is something strange happened in my calculation. When I increase the > >> ecutwfc, the shielding tensor of C did not converge: > >> 40ry:43ppm. 50ry:40ppm. 60ry:46ppm. 70ry:55ppm. 80ry:54ppm. 90ry: 43ppm. > >> 100ry:30ppm. 110ry:27ppm. 120ry:39ppm. 130ry:62ppm. 140ry:85ppm. > Your input looks correct, except for an isolated system you don't > need the macroscopic shape correction. Later tonight or tomorrow, > I'll investigate the problem. > > > Cheers, > Davide >
