Thank you very much. Alan.
2017-05-13 11:09 GMT-03:00 Davide Ceresoli <[email protected]>: > Dear Alan, > I think that there is no problem in doing a G=0 response > with a shifted mesh. The response is at G=0, hence it couples > wfcs at the same k. The susceptibility depends a lot on k-points > sampling and if your system has a vanishing band gap, convergence > can be a nightmare. > By default the macroscopic shape is diagonal: > nmr_macroscopic_shape(:,:) = 0.d0 > nmr_macroscopic_shape(1,1) = 2.d0 / 3.d0 > nmr_macroscopic_shape(2,2) = 2.d0 / 3.d0 > nmr_macroscopic_shape(3,3) = 2.d0 / 3.d0 > You can change the component (demagnetizing field) in the input file. > > Good luck for your calculations! > > Best, > Davide > > > > On 05/12/2017 07:47 PM, Ambrozio wrote: > > Dear QE users and Developers, > > > > I'm working with NMR calculations in Gipaw. Recently I did some shielding > > calculations and I have some questions regarding the magnetic > susceptibility. > > The article from developers Mauri et al (*PRL 77, 26, 1996*) explain > that the > > shielding of a bulk of a periodic system is also periodic (i.e. has the > same > > periodicity of *G*, the reciprocal lattice vectors), and it is > proportional to > > the magnetic susceptibility matrix. In the paper Mauri did a short > discussion > > about the macroscopic susceptibility, which is calculated at *G=0*. > Follow my > > questions: > > > > i) Assuming that the macroscopic susceptibility is calculating at gamma > point > > (*G=0*) and depends of the sample's shape, Does make sense to do a NMR > > calculation with automatic kpoints (monkhorst pack grid) that does not > include > > the gamma point? It is mandatory to including the gamma point when the > shape > > correction is .true.? > > > > ii) Does the susceptibility depends of the supercell size? I found very > > different susceptibilities for the same material (AB graphite) changing > the > > supercell size. > > > > iii) Why the susceptibility matrix is not diagonal when the shape > correction is > > .true.? Assuming the Mauri paper I think it doens't make sense. Help me > to > > understand... > > > > > > I appreciate any help, > > > > Thanks in advance, > > > > > > Alan. > > > > > > > > -- > > > > Alan J. Romanel Ambrozio > > Bacharel em Física > > Mestre em Eng. de Materiais > > Doutorando em Física - PPGFis > > > > > > > > -- > +--------------------------------------------------------------+ > Davide Ceresoli > CNR Institute of Molecular Science and Technology (CNR-ISTM) > c/o University of Milan, via Golgi 19, 20133 Milan, Italy > Email: [email protected] > Phone: +39-02-50314276, +39-347-1001570 (mobile) > Skype: dceresoli > Website: http://sites.google.com/site/dceresoli/ > +--------------------------------------------------------------+ > _______________________________________________ > Pw_forum mailing list > [email protected] > http://pwscf.org/mailman/listinfo/pw_forum > -- Alan J. Romanel Ambrozio Bacharel em Física Mestre em Eng. de Materiais Doutorando em Física - PPGFis
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