The definition of the FERMI ENERGY that I gave is correct for every material: 
The Fermi energy is the energy of the highest occupied state at Zero 
temperature.
It does not depend wheter or not your material is a metal, an intrinsic 
semiconductor, an doped semiconductor, an insulator, or anything else.

Indeed, for metals the Fermi energy corresponds to the chemical potential (the 
quantity  that enters the Fermi-Dirac distribution)  at Zero temperature.
but the chemical potential of a metal will also depend on temperature (Note: 
the chemical potential, not the Fermi energy, depends on temperature.).

The Zero used in the electronic structure plots (DOS, band structure, etc.) of 
Wien2k is the Fermi energy as defined above,
therefore, it is correct to have the Zero at the top of the valence band.

By the way, you never defined what you mean with "Fermi level" and why it must 
be in the middle of the band gap.
If you define for whatever reason that "Fermi level" is "the energy in the 
middle of the band gap" then your question does not make sense. 
However, if you like to stay with youre middle of the gap definition, then you 
should give a mathematical and physical proof that this is something 
usefull for all shapes of the density of states of a semi-conductor.

If you like to know where the chemical potential in a certain semi-conducting 
material is then you may check with Boltztrap,
you have to do the same that I did when its still not implemented there , 
change the code to include it.

Just to mention, it is not my habit to answer questions about Wien2k that are 
send directly to me, please use the forum.

Ciao
Gerhard

DEEP THOUGHT in D. Adams; Hitchhikers Guide to the Galaxy:
"I think the problem, to be quite honest with you,
is that you have never actually known what the question is."

====================================
Dr. Gerhard H. Fecher
Institut of Inorganic and Analytical Chemistry
Johannes Gutenberg - University
55099 Mainz
and
Max Planck Institute for Chemical Physics of Solids
01187 Dresden
________________________________________
Von: tarek.ben-n...@laposte.net [tarek.ben-n...@laposte.net]
Gesendet: Donnerstag, 20. Oktober 2016 14:48
An: Fecher, Gerhard
Betreff: Re:Fermi level

Dear Gerhard,

Thank you for your reply but this definition of Fermi level is correct for a 
metal and not for a semiconductor so in band structure putting fermi level at 
the top of valence band is wrong.

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