[Wien] absoption coefficients calculation

[Zhiyong Zhang]

Deal All, 

I have a few questions about the calculation of absorption coefficients with spin-orbit interactions. With the converged spin-orbit calculations, I ran 
(1)x lapw2 -fermi -up 
(2)x optic -up; 
(3) x joint -up; 
(4) then copied case.jointup to case.joint; 
(5)x kram, 

all with spin-orbit options. 

Since it is a spin-orbit calculations, I chose 9 for the number of choices (columns in *outmat) in case.inop and also 9 for NUMBER OF COLUMNS in case.injoint. The system has 3-fold and inversion symmetry in hcp lattice.

For the absorption coefficients, there are 9 components, with large contributions with xy >> xx=yy>zz and all the other components are essentially zero.     

Here are some of my questions: 

(1)Are there any good references for the symmetry properties of the absorption coefficients? 

(2)To get the total absorption coefficients do I simply sum up all the xx, yy, ... components? 

(3)As noticed, the xx and yy components are degenerate, which is expected (correct me if I am wrong here). However the yx component is large but the xy components are almost zero. Should I also expect degeneracy in xy and yx components? 

(4)Is there a general selection based on symmetry for these components? How do I interpret each component physically? 

(5)The energy window I selected for the momentum matrix calculation is large, from -5.0 to 8 eV. So I wuold not expect that this will break the symmetry for the absorption coefficients.

Any comments and suggestions would be greatly appreciated. 

Thank you very much fro your attention. 

Zhiyong