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

[#TAO JUNGUANG#]

Dear Martinez,
Thanks for suggestion. 
The gap of TiO2 is occurred at (0 0 0) , so I just take a rough analysis at this point. By the way, do you know how to plot out the band structure based on the output file of pwscf? Thx in advance.

Regards!

Tao Junguang 

-----邮件原件-----
发件人: pw_forum-admin at pwscf.org [mailto:pw_forum-admin at pwscf.org] 代表 Miguel Martinez
发送时间: 2005年10月26日 23:25
收件人: pw_forum at pwscf.org
主题: Re: [Pw_forum] why I can not get the correct band gap of TiO2?

#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
Facultad de Ciencia y Tecnología
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48080 Bilbao (Spain)
Fax:  +34 94 601 3500
Tlf:  +34 94 601 5437
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