[Pw_forum] Fail to predict semiconductor

[Giuseppe Mattioli]

Dear Iwan
I would try to use a larger supercell. The strong interaction between the periodically repeated 
images of your Ti atoms may induce a spurious, huge dispersion of the band containing the two excess 
electrons.
HTH

Giuseppe

On Wednesday 23 January 2013 06:50:35 Iwan Darmadi wrote:
> Dear all,
> 
> 
> I have calculated electronic structure of Ti doped ZnO in both GGA and
> GGA+U scheme. Both scheme predicts Ti doped ZnO is metallic. In contrary,
> Ti doped ZnO is well known as semiconductor experimentally. At first
> glance, I thought it was local minimum problem of DFT+U (like FeO problem
> in Mr. Himmetoglu's tutorial). Then I try to copy Mr. Himmetoglu's trick
> to override a "suspected" fully occupied orbitals of Ti. Sadly, nothing
> change,  it's still a metallic.
> 
> 
> Now, I am confused whether this is a really local minimum problem or
> intrinsic limitation of DFT it self.
> 
> 
> Do anyone here have suggestions so I can get semiconductor Ti doped ZnO in
> the calculation ?
> 
> 
> Ps.
> 
> I have also attached my input and output file.
> 
> ***
> 
> Iwan Darmadi
>  Undergrad.Student - Department of Physics
> 
>  Universitas Indonesia

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   Giuseppe Mattioli                            
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