[Wien] Suspicious Fermi energy values

[dileep at jncasr.ac.in]

Dear users,

I am studying the band gap and the valence band offsets of ZnO and ZnS using mBJ exchange correlation potential in WIEN2k12.1 . It is well established using theory and experiment (also it is intuitive)that the valence band offset of ZnS is higher in energy than that of ZnO by ~ 1 eV (DOI: 10.1103/PhysRevLett.97.146403). But I am getting the valence band offsets
 
ZnO - 0.39378 Ry
ZnS - 0.24021 Ry

What could have gone wrong?
I am using a single unit cell in both cases with Wurtzite structrures
I am using 76 irreducible k points in both cases (put 1000 as input in k-gen).
RKmax in both cases are 7.00
The c-parameter in mBJ potential were given according to the 'P-semiconductor' scheme in 10.1103/PhysRevB.85.155109

-Regards
 Dileep Krishnan
 c/o Dr. Ranjan Datta
 ICMS, JNCASR,
 Jakkur
 Bangalore, India - 560064