[Pw_forum] Fwd:NMR of benzene

[nlu at mail.ustc.edu.cn]

Sincerely thanks to Davide for your explaination. I would hope your further
investigation.

Best wishes.
Ning Lu

ÔÚÄúµÄÀ´ÐÅÖÐÔø¾­Ìáµ½:
>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
>