[Pw_forum] ZnO(1010) surface BandGap

[Giuseppe Mattioli]

Dear Meysam
You cannot (easily) improve your calculation... Due to static correlation 
error, there is a strong interaction between the Zn 3d band and the O 2p band 
which push up the valence band maximum. It does not depend on the slab or 
bulk geometry. Your weapons could be some hybrid functional or a SIC 
scheme...
HTH

Giuseppe

On Friday 18 February 2011 12:12:10 meysam pazoki wrote:
> Dear PWSCF users
> In scf calculations of my 64 atom ZnO supercell(wich is relaxed by bfgs
> method),the band gap of ZnO (1010) surface approximately disapear.
> Espresso gives a 0.2 eV gap for this system in GGA functional.The surface
> consist of 4 layers of ZnO bulk unit cell.
> Is it due to surface states or not?how can i improve my calculations?
> Thanks in advance
> Best Regards
> Meysam Pazoki
> Ph.D student of physics
> SUT



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   Giuseppe Mattioli                            
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