[Pw_forum] why I can not get the correct band gap of TiO2?

[Miguel Martinez]

#TAO JUNGUANG# wrote:
> End of band structure calculation
>           k = 0.0000 0.0000 0.0000     band energies (ev):
[...]
> I think the band gap is (1.4602-(-9.1108)=10.571eV)

Hmmm... maybe I am wrong, but I would think this is the gap...
AT (0,0,0)!!!

You should plot the bands in several directions to see what the gap is. 
It might well be an indirect gap (the valence band maxima and the 
conduction band minima occur at different q_points), and, as such, only 
observable in a plot or in a very careful analysis.

Hope it helps,

Miguel


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Miguel Martínez Canales
Dto. Física de la Materia Condensada
UPV/EHU
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