[Pw_forum] HSE&PBE0 problem

[debbichi mourad]

Dear pwscf users,

I performed some calculations by using PBE0 and HSE on the ZnO system. When I used a supercell with 4 atoms , 
I obtained a Fermi levels comparable to those calculate without  hybrid functional (Ef= 7.68 eV) .
 Almost, the same result is obtained for a supercell with 16 atoms.
But (for a supercell with 16 atoms) with PBE0 and HSE Ef becomes large (Ef~28,258 eV).

Why such a problem occurs?
Thanks a lot  in advance
Mourad

 
DEBBICHI Mourad
Unité de Recherche Physique des Solides,99/UR/13-19,
Département de Physique, Faculté des Science de Monastir,
Avenue de l'Environnement 5019, Monastir Tunisie.
tél:+21697487042
mourad_fsm at yahoo.fr
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