[Wien] Fermi level after mBJ calculation

[Peter Blaha]

Clearly, you should in general NOT use EF from case.scf2up in a band structure calculation.
In particular when your system is METALLIC, with a "bandstructure k-mesh" one cannot perform a
good BZ integration and EF will be wrong!
Of course, you have to increase the regular k-mesh of the scf runs, until EF is stable.

Of course, the situation may be different for an insulator because
in the scf k-mesh due to "shifted k-meshes", the VBM may not be in your mesh and thus you may miss
the highest occupied state. Eventually you will have the VBM in your bandstructure mesh
(eg. the Gamma point), but there are numerous cases, where the VBM can also somewhere in
the BZ and NOT at a high symmetry point.
Thus for an insulator, I'd call the proper EF as the highest energy you can get of the l
ast occupied band.



Am 26.10.2012 18:42, schrieb Kamil Klier:
> Colleagues,
>
> Please advise whether, following a converged LDA+U and mBJ calculation, the Fermi energy to be inserted into case.insp after the sequence:
>
> x lapw1 -c -p -up -band
> x lapw1 -c -p -dn -band
> x lapwso -c -orb -p -up
> x lapw2 -c -so -p -qtl -up -band
> x lapw2 -c -so -p -qtl -dn -band
>
> is to be found from case.scf2up/dn (grep :FER case.scf2up), not from previously saved case.scf (cf. paragraph 8.3.2, line 9, efermi in the Wien2k manual).
>
> The -band calculation uses different number of k-points read from case.klist_band (e.g. 61 k-points for the hcp list) than the preceding mBJ calculation with fewer
> k-points. Is this the reason for the difference between :FER from case.scf and case.scf2up/dn?  Would the difference be removed if case.klist and case.klist_band were
> identical?
>
> Thanks,
>
> Kamil Klier
> Lehigh University
>
>
>
>
>
>
>
>
>
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-- 
-----------------------------------------
Peter Blaha
Inst. Materials Chemistry, TU Vienna
Getreidemarkt 9, A-1060 Vienna, Austria
Tel: +43-1-5880115671
Fax: +43-1-5880115698
email: pblaha at theochem.tuwien.ac.at
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