[Wien] Diference in EFG values

[Stefaan Cottenier]

> According to my understanding, core-state with tag F are valence states.
> AM I right? If yes then why it is taking 3P states as valence states?
> The valence electrons for Co are 3d7, 4s2.

You use the words 'valence electrons' in the traditional 'chemical' way 
as states outside the noble gas core. In the context of the DFT, the 
term 'valence electrons' refers to all states that are not forced to 
behave as in a free atom (i.e. they allow to feel the presence of the 
surrounding crystal).

You cannot avoid to use Co-3p as valence states with wien2k, the 
numerics would break down if you didn't.

Your output shows that wien2k has Co-3s and Co-3p as valence states, 
whereas vasp considers these as core states (i.e. they will not 
contribute to the EFG in vasp). Co-3s will never contribute to the EFG 
(spherical), whereas Co-3p could (albeit not very likely).

First consider the suggestion by Peter Blaha: make sure you have 
identical XC-functionals in both codes, and inspect whether all magnetic 
moments and the DOS and band structure pictures agree for both codes.

If that is all right, then use the procedure to which I refered in my 
previous post to isolate the EFG contribution of Co-3p. If that is 
nearly zero, I don't know what is going on. If it would be equal to the 
vasp-wien2k difference, then you have found the origin of your problem.

Stefaan