[Pw_forum] Which Fermi level is right?

[Paolo Giannozzi]

On Jul 16, 2007, at 18:57 , Nkrumah-Buandoh George_Kofi wrote:

> [...] For the scf calculation I used occupation='smearing', the  
> fermi energy
> is 7.5440 eV. For the density of states I used  
> occupation='tetrahedra', and
> the Fermi energy is 6.4196 eV
>
> Why do the two different methods give two different results?

they don't. If both calculations are performed with a k-point grid
that allows a decent description of the Fermi surface, and if the
gaussian broadening has an appropriate value, you should get
similar results for both KS eigenvalues and Fermi energy. If you
don't , you should carefully check your input data. Remember
that atomic positions are read from input data, not from the
data file, in a nscf calculation

Paolo
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Paolo Giannozzi, Democritos and University of Udine, Italy