[Wien] Whether or not can we predict band gap with scissors operator?

[Joey Davis]

Dear WIEN users:
   
     I am trying to calculate the optical and electronic properties of a compound. I only have the structure and optical conductivity spectra got from experiment. 
   
  You know that the DFT cannot give the accurate band gap. Scissors operator is   introduced, that is, the conduction bands are shifted. Then the spectra can be similar to the experiment.
   
  Now, we got the band gap (Eg1) from calculation. With scissors operator (Eg2), the shape of the mainly peaks in the optical conductivity spectra agrees well with the spectra of experiment. Can we declare the real band gap (the band gap from experiment) is equal to Eg1 +Eg2?  Can we regard that this is a method to get the band gap in our compound? 
   
  Can anyone tell me, or give me some references about the question?
   
  Many thanks!
   
  Joey Davis
   

 
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