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["Bohdan Andriyevsky" <bandri@tu.koszalin.pl>]

Dear Abinit Users,

When I have calculated the conductivity spectrum g(E) of my crystal (Eg > 5 eV) using the 'abinis' and 'conducti' exe-files, I have calculated the imaginary part of the dielectric permittivity epsilon'' using the relation:

g=2*pi*f*epsilon0*epsilon'' , where f=E/h (h=6.62E-34 is Planck constant), and epsilon0=8.85E-12.

The structure of the spectrum epsilon''(E) obtained agrees well with the corresponding experimental data. Then I have calculated the real part of the dielectric permittivity epsilon'(E) using the known Kramers-Kronig relation:

epsilon'(E)-1=(2/pi)*integral{[t*epsilon''(t)*dt]/[t^2-E^2]}.

The magnitude of the epsilon'(0)=1.4 obtained by this calculation is much smaller than the experimental one and the analogous magnitude obtained from the RF calculations (2.5) using the Abinit.

Maybe anyone already has done similar analysis? I will be thankful for any advices to resolve my problem.

 

Regards,

Bohdan Andriyevsky