[DFTB-Plus-User] Fermi level in DOS and Band calculation

[Bálint Aradi]

Dear R,

> I have a doubt regarding the Fermi Energy.
> It differ in the DOS calculation and in the subsequent calculation for
> the Band Structure. Which is more likely to be correct in your opinion?
> Please let me know if you need any further data.
> Best regards: R

 The position of the Fermi energy heavily depends on your sampling of
the Brillouin-zone. Usually, for DOS calculation you choose a proper
sampling, while for band structure you sample along high symmetry lines.
So in the former case it should be more accurate.

  Please note, however, that due to numerical issues, in case of
isolators the position of the Fermi level is somewhat arbitrary between
the highest occupied and the lowest unoccupied state. At 0K it should be
theoretically in the middle between them, and by raising temperature
move depending on the density of states at the band edges. But at lower
temperatures and big gaps it is hard to find that position numerically.
If you need a practical reference in those cases, take the VB edge.

 Best regards,

   Bálint

-- 
Dr. Bálint Aradi
Bremen Center for Computational Materials Science, University of Bremen
http://www.bccms.uni-bremen.de/cms/people/b_aradi/


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