[Wien] [partially solved] help is needed for case.inkram file (scissors operator)

[Xavier Rocquefelte]

Dear Bhamu

The Fermi level when expressed in Rydberg is given with respect to the 
printed value in the scf file.

In contrast, by convention the Fermi level is fixed at 0 when given in eV.

In your case, if you have the following data :FER = +0.134 Ry, it means 
that you must supply this value in the case.insp file for plotting band 
structures.

Concerning the use of a scissors operator (SO), you indeed must define 
this value in the case.inkram file. The scissors operator must be 
expressed in eV and is not related to the Fermi level. You should first 
simulate the imaginary part of the dielectric function (eps2) and then 
compare to the experimental data you have. If the DFT band gap is too 
small by X eV, you must redo "x kram" with a case.inkram file containing 
a SO of X eV.

Regards

Xavier


Le 03/12/2016 à 11:03, Dr. K. C. Bhamu a écrit :
>
> Dear Experts,
> I applied scissors operator in energy bands (now Ef is at VMB, 
> previously it was in the middle of VBM and CMB).
>
> I reduced :FER in the case.insp.
> I still have two queries:
>
> 1) I think we do not need to change anything for DOSS. is it?
> 2) If I CBM upward, should I adjust/ apply scissors operator in 
> case.inkram file:
>
> _case.inkram_
>
>   0.1    Gamma: broadening of interband spectrum
>   0.0    energy shift (s3) inissors operator) *>>>>>       I reduced 
> :FER in case.insp by 0.134513495 Ryd. How to use it here + 0.134513495 
> or *
> *    -0.134513495)?? *
>   0      add intraband contributions? yes/no: 1/0
>  12.60   plasma frequencies  (from joint, opt 6)
>   0.20   Gammas for Drude terms
>
>
> Yours Sincerely
>
> Bhamu
>
> On Fri, Dec 2, 2016 at 7:29 PM, Dr. K. C. Bhamu <kcbhamu85 at gmail.com 
> <mailto:kcbhamu85 at gmail.com>> wrote:
>
>     Dear Experts
>
>     I tried to get band structure of wide band gap semiconductor. When
>     I preformed usual DFT of DFT+U, I see my Ef is at VBM. But when I
>     calculated PBE+mBJ+U, my VBM shifted down (if some one want to
>     see, I will email it as it is not possible to attach here) by a
>     value of -1.24689eV at M point, -1.24913eV at H point.
>
>     So, by going through literature and from mailing list, I came to
>     know that I have to apply scissors operator.
>     I went through the following important links
>
>     http://www.mail-archive.com/wien@zeus.theochem.tuwien.ac.at/msg11416.html
>     <http://www.mail-archive.com/wien@zeus.theochem.tuwien.ac.at/msg11416.html>
>     http://www.mail-archive.com/wien@zeus.theochem.tuwien.ac.at/msg02523.html
>     <http://www.mail-archive.com/wien@zeus.theochem.tuwien.ac.at/msg02523.html>
>     http://www.mail-archive.com/wien@zeus.theochem.tuwien.ac.at/msg14559.html
>     <http://www.mail-archive.com/wien@zeus.theochem.tuwien.ac.at/msg14559.html>
>     http://www.mail-archive.com/wien@zeus.theochem.tuwien.ac.at/msg13025.html
>     <http://www.mail-archive.com/wien@zeus.theochem.tuwien.ac.at/msg13025.html>
>
>     to see how I can apply this operation.
>     I could not get perfectly and puzzling, how to apply scissors
>     operator.
>
>     If I understood well then I should convert above mentioned energy
>     into Ry and put into the following case files:
>
>     1) _case.int <http://case.int> for DOSS, _*but where?*
>     pbe             #Title
>      -1.50   0.002   3.500  0.003 #Emin, DE, Emax, Gauss-Broad
>       11   N   0.000 #Number of DOS-cases,G/L/B broadening (Ry)
>
>     2) _in case.insp for band _
>     ### Data configuration
>     -21.0  12.0  2                      # energy range, energy switch
>     (1:Ry, 2:eV)
>     1      0.5362044322    # Fermi switch,  Fermi-level (in Ry units)
>     *>> If i am not wrong, I should add the rubbish energy into this Ef*
>     1   999                            # number of bands for heavier
>     plotting 1,1
>     0      1    0.2                    # jatom, jtype, size  of
>     heavier plotting
>
>      and
>
>     3) _in case.inkram_
>
>       0.1    Gamma: broadening of interband spectrum
>       0.0    energy shift (scissors operator) >>>>> *here?? *
>       0      add intraband contributions? yes/no: 1/0
>      12.60   plasma frequencies  (from joint, opt 6)
>       0.20   Gammas for Drude terms
>
>
>     _Now another query is:_
>     Form the below dispersion curve, I am getting VBM at H but there
>     is a small bump (peak) between K and G point which is 0.14eV
>     towards the Ef.
>     Can ignore this value? or I should apply this value (-1.1898eV or
>     -0.0874486553Ryd) for scissors operator?
>
>
>
>
>     Sincerely
>     Bhamu
>
>
>
>
>
>
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