[Pw_forum] Gipaw - Magnetic susceptibility

[Ambrozio]

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
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.quantum-espresso.org/pipermail/users/attachments/20170512/47cc1999/attachment.html>