[Pw_forum] band gap from hybrid pseudopotentials

[毛飞]

Hello, Msaqlain
> -----原始邮件-----
> 发件人: saqlain <saqlain at bilkent.edu.tr>
> 发送时间: 2016年8月5日 星期五
> 收件人: pw_forum at pwscf.org
> 抄送: 
> 主题: [Pw_forum] band gap from hybrid pseudopotentials
> 
> Dear QE users
> 
> I would like to use QE for calculating band gap with hybrid 
> pseusopotentials approach.
> 
> after going from the discussions available at different sites, I have 
> done the calculation in this way: vc-relax the system, did scf and then 
> nscf followed by band structure calculation. My questions are,
> 
> 1. How can I now extract the band gap from the file generated by bands.x?
The output file generated by bands.x can be processed by plotbands.x to plot the band structure, then you can obtain the band gap.
 
> 2. in the scf and nscf output files, I can't see Fermi energy. How can I 
> know about the Fermi energy?
Do you add some smearing in these calculations?
 
> 3. The scf and nscf files contain, highest occupied and lowest occupied 
> levels? what is meaning of this? does the highest occupied level mean 
> Fermi energy?
No, for insulators (which shows the electronic band gap), the Fermi energy stays between the HOMO and LUMO
 
> 4. does the difference of highest occupied and lowest occupied level 
> correspond to band gap?
No, the band gap Eg = I-A.
 
regards
evan
> your response would be highly appreciated
> 
> Msaqlain
> 
> Bilknet, Ankara. Turkey
> 
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