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Kramers–Kronig relations and contributions to nonlinear response

Elk Users
2015-09-20
2015-09-30
  • amirhossein

    amirhossein - 2015-09-20

    Dear elk developers
    I have 3 basic questions and I need your help as soon as possible.
    1- is it necessary to use Kramers–Kronig relations for calculating imaginary and real parts of linear and nonlinear optical response?
    2- Elk is based on Kramers-Kronig relations or not?
    3-As you know, the SHG has 3 contributions: the intra-band, the inter-band and the modulation terms. why Elk generates results only for inter- and intra-band parts and there is no file for modulation part?
    thanks in advance

     
  • Sangeeta Sharma

    Sangeeta Sharma - 2015-09-21
    1. No KK relation is not necessary. One can calculate whole comples response using perturbation theory.
    2. No Elk does not use KK relation explicitly.
    3. modulation term is not written to a file. But is added to produce the total response.
     
    • amirhossein

      amirhossein - 2015-09-22

      Dear sharma
      thank you very much
      I wish you all the best in your life

       
      • amirhossein

        amirhossein - 2015-09-26

        Dear sharma
        As you have said the kramers-kronig relation is not implemented in elk package. Hence I need more information about the procedure that elk uses for calculating imaginary and real parts of linear and nonlinear optical response. I want to write these informations in my thesis. please give me more information.
        thanks a lot

         
  • amirhossein

    amirhossein - 2015-09-29

    Dear elk developer
    As you know, ELK is not based on kramers-kronig relations. Please give me more information about the procedure that ELK uses for calculating the imaginary and real parts of linear and nonlinear optical susceptibilities. if you know useful references, please tell me.
    thanks a lot

     
  • Markus

    Markus - 2015-09-30

    Dear Amir,

    look into the routine dielectric.f90, there's a citation of the formula that is used for the evaluation of the optical conductivity tensor in its full complex form: Physica Scripta T109, 170 (2004). For details of the calculation, look through the code. It's commented and not very hard to understand.

    In the routine nonlinopt.f90 there are some references to articles describing how the second harmonic generation is computed.

    Best regards
    Markus

     

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