[Pw_forum] inconsistent quadrupolar coupling from gipaw calculation

[Jia Chen]

Dear All,

I am working on calculating nmr parameters with gipaw code. I have two
settings: one with norm-conserving gipaw pesudopotentials which has some
semi-core states, and the other with ultra-soft gipaw pseudopotentials.
Electronic structure eigenvalues from pwscf look similar, and
chemical-shift are not far away from each other. The issue is quadrupolar
coupling, for Co, norm-conserving calculation gives 0.5MHz and ultra-soft
gives 1.5MHz. It seems to me a significant discrepancy.  I don't know what
caused the inconsistency, and which one is more reliable. I appreciate any
insight on this problem.

One thing about norm-conserving calculation is that the code gives warming
about some orbitals has zero norm. I don't know if that could be of
concern.

Cheers
Jia
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