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

Dear Konstantin,
You are maybe right. I am not familiar with annddb code. However, the 
magnitudes of epsilon'(0 eV) obtained for my crystal using 'optic' were 
very small and very far form the experimental square of refractive index 
in the visible range (the range of transparency of my crystal). Another 
reason of this discrepancy may be that my crystal is of molecular type 
with low density (1.5 g/cm3). So, it is probably not a good object for 
the 'abinit'.

Regards,
Bohdan Andriyevsky

Konstantin Rushchanskii napisał(a):

> Dear Bohdan,
>
>  
>
> > I had right the same problem with another crystal: the calculated
> > magnitudes of epsilon' (0 eV) obtained by 'optic' and 'anaddb' were
> > very different. Unfortunately, I had no obtained an answer on similar
> > question. The value of epsilon' (0 eV) obtained with 'anaddb' seem to
> > be right.
> >    
>
>
> May be the answer is, that anaddb takes into account also the phonon
> degrees of freedom (and corresponding part of esilon (0eV)), and
> utilizing the optic utility you have only electronic contribution to
> espilon (0eV)?
>
> Sincerely,
> K.Rushchanskii
>
>
>