Optical Properties: DFT, Pseudopotential, Plasma Frequency, Transmission

[bahaar]

Hello

1- I calculate optical properties of a pure compound in framework of DFT with pseudopotential by software. I get several picks in loss function. Does only the highest , determine plasma frequency or all of them with different density of valence electrons?

2-can we conclude the picks of the ε1 always show the maximum of transmisson?

Thanks

 

[bahaar]

Hi
Perhaps i should clear more my question. Please guide me.
I calculate the optical properties of SrS compound.I have two question:
1. In the loss function, there are several picks. I want determine plasma frequensy. Does only the highest pick show position of plasma freqeuncy and other picks show transition energies? can we tell the other picks are plasma frequencies correspond to differnt densities of valence electrons?
2. I used HGH pseudopotentials. 10 electrons of [38]Sr and 6 electrons of [16]S are used as valences electrons in these psedopotentials. So i plus these two values (10+6=16) and divide to two atoms's volume (1/4 volume of cell) and used the

w_p =√(ne²/ε₀m) to get plasma energy, but this value is 7-8ev less than plasma energy that achieved from highest pick in loss function.These means i must use approximately 30 electrons to calcuate n=density of valence electrons . The plasma energy of highest pick are correspond approximately to other theory results in different papers. please help me to solve it.
Thanks alot.

 

[DrDu]

You are talking about peaks (not picks)?
Maybe this article is helpful:
http://www.sciencedirect.com/science/article/pii/0038109882905555

 

[bahaar]

Hi.
Yes my means was peak. It is really embarrassing.
Thanks a lot for your reply.