The ABINIT Users Mailing List ( CLOSED )

[Xavier Gonze <gonze@pcpm.ucl.ac.be>]

Dear Kristopher Andersen,

Kristopher Andersen wrote:
> I'm puzzled by the Fermi energy in ABINIT. I've been running some
> calculations on ZnSe and for the band energies at k = 0 I get
>
>  kpt#   1, nband= 10, wtk=  0.00800, kpt=  0.0000  0.0000  0.0000
>   -0.53351  -0.29563  -0.29563	-0.29563  -0.28408  
>   -0.28408  -0.05693  -0.05693  -0.05693  -0.01967
>
> The Fermi energy isn't printed out anywhere in the output file, but is
> supposedly written to the unformatted _WFK and _DEN files. When I look
> there, they both give the Fermi energy (variable fermie) to be 0.0?
> Clearly this would be in the conduction band given the band energies
> above, since ZnSe has 9 occupied bands and is a direct gap
> semiconductor.

The "Fermi energy" is well-defined for metallic occupations schemes (or 
smeared occupation schemes). You get it with ABINIT when occopt
is between 3 and 8.
This is not the case for a semiconductor at 0K . That
is why ABINIT does not deliver it. In the files, the field
is filled with a zero (no meaning, though ...).

I guess that you are interested with the energy of the
highest occupied orbital. For the time being, you have
to examine the file ... it is not determined automatically...
but it should be easily coded ...

Good continuation,
Xavier