band occupation

[IBRAHIM]

Dear All,

For magnetic metallic system, the sum of the band occupancies in OUTCAR (average over all bands and kpoints) is higher than the total number of valence electrons. Why that happened? this is neutral system.
At single gamma point the occupation is same as the number of electrons.

Also that gives band gap of about 0.06 eV (some partial occupancies are found) but DOS show metallic.

Many thanks in advance,
Ibrahim

[fabien_tran1]

Hi,

How did you count the total number of electrons? Are you sure that you did it correctly by taking into account the weight of the k-points?

The band gap from the scf calculation and the DOS may give slightly different results if different methods for the smearing are used. 0.06 eV is quite small.

[IBRAHIM]

Thanks for your reply.

I got mangntization of 8 in std.out but when I checked the OUTCAR I found the difference between spin up and down occupied bands at some kpoints is not 8.

So, I just cheched the diffence between total occupation of occupied spin up and spin down bands then the avarage per kpoints is not also 8.

Is it normal?

Best regards,
Ibrahim

[fabien_tran1]

Indeed, for a metal the spin up and down occupancies may differ from one k-point to another, and therefore also the difference bwtween up and down. As I wrote in my previous answer you need to take into account the weight associated with each k-point in the IBZ to calculate the total number of up and down electrons (below "irreducible k-points:" in OUTCAR). Did you do it?

Just to mention that also in OUTCAR the written magnetization is 8:
"number of electron 28.0000080 magnetization 8.0000030"

[IBRAHIM]

Thank you very much.

Yes, I did not take into account the weight of KPOINTS.

Now it is clear why I got that difference.

Best regards,
Ibrahim