Optical conductivity

The functionality suffers from some program bugs. The revised code will be released in future.

The optical conductivity can be evaluated within linear response theory [42]. OpenMX Ver. 3.5 supports the calculation for only the collinear cluster calculation. If you want to calculate the optical conductivity of molecular systems, you can calculate it by the following two steps:

(1) SCF calculation

First, you would perform a collinear cluster calculation using an input file Methane_OC.dat in the directory 'work' as an example. Then, you have to set the following two keywords 'Dos.fileout' and 'OpticalConductivity.fileout' as follows:

    Dos.fileout                    on    # on|off, default=off 
    OpticalConductivity.fileout    on    # on|off, default=off

When the execution is completed normally, then you can find files, *.optical and *.Dos.val, in the directory 'work'.

(2) Calculation of optical conductivity

Let us make a program code for calculating the optical conductivity. Move the directory 'source' and then compile as follows:

    % make OpticalConductivityMain
  

When the compile is completed normally, then you can find a executable file 'OpticalConductivityMain' in the directory 'work'. The optical conductivity can be calculated from the files '*.optical' and '*.Dos.val' using the program 'OpticalConductivityMain' as follows:

    % ./OpticalConductivityMain met.optical met.Dos.val met.optout
  

where a methane molecule is considered as an example. Then, you are interactively asked from the program as follow:

     # freqmax=100.000000
     # gaussian=0.036749
     freqmax (Hartree)=? 3
     freq mech=? 1000

In the output file 'met.optout' the second, third, and fourth columns correspond to the frequency (Hartree) and optical conductivity (arbitrary unit) for up- and down-spins, respectively.