Absorption Spectrum

[liusjtc]

Hi

As I know that the BLongDir is the direction for the absorption in the bse solution and the LongDrXs for the RPA calculation of the static screening.
But I am still not sure if I want to calculate the ny of a body media , may I just set nlongdir to 010 and longdir to 100.

Thanks
Best regards
Liu Shijie
Shanghai Jiaotong university

[Daniele Varsano]

Dear Liu,
can you explicitly explain what you mean by "ny of a body media" ?

Best,

Daniele

[liusjtc]

Dear Daniele

Sry for the misunderstanding. which i want to ask is how to calculate the n_y of a biaxial crystal. i got little confused about the parameter nlongdir and longer.
More specifically, if I want to calculate the n_o and n_e of a uniaxial crystal, should i set the nlongdir to [100] with longdir set to [100] for n_o and set nlongdir to [001] with longdir also set to [100] for n_e. Is that right?


Thanks
Best regards
Liu Shijie
Shanghai Jiaotong university

[Daniele Varsano]

Dear Liu,
sorry bu again not very clear.
I can't understand what do you mean by "nlongdir", "longer", "longdir".
Anyway as you said in the first post both BLongDir and LongDrXs indicates you the "cartesian" direction of the light polarization.
If your system is anysotropic they are not equivalent, and something LongDrXs (111) it is a sort of average over the space for the calculation of the screening.
Next BLongDir will give you the direction of the absorption, namely (100), (010), (001), will give you \eps_xx, \eps_yy, eps_zz.

If you set your system for instances being x direction (100) the optical axis, BLongDir (100) will give you n_e, (010) and (001) should be equivalent and they will give you n_o.
Hope it helps, but not totally sure I've understood your question.

Best,
Daniele