Optical Properties: DFT, Pseudopotential, Plasma Frequency, Transmission

In summary, the conversation is about calculating the optical properties of a compound using DFT with pseudopotentials and determining the plasma frequency. There are multiple peaks in the loss function, and it is questioned if only the highest peak determines the plasma frequency or if the other peaks correspond to different densities of valence electrons. There is also discussion about the use of pseudopotentials and the calculation of plasma energy. The conversation ends with a helpful article being suggested and a clarification of the term "peaks."
  • #1
bahaar
9
0
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
 
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  • #2
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

wp =√(ne20m) 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.
 
  • #3
You are talking about peaks (not picks)?
Maybe this article is helpful:
http://www.sciencedirect.com/science/article/pii/0038109882905555
 
  • #4
Hi.
Yes my means was peak. It is really embarrassing:blushing:.
Thanks a lot for your reply:biggrin:.
 

1. What is DFT and how does it relate to optical properties?

DFT stands for Density Functional Theory, which is a computational method used to study the electronic structure and properties of molecules and materials. In terms of optical properties, DFT can be used to calculate the electronic polarizability of a material, which is a crucial factor in determining its optical properties such as refractive index and absorption coefficient.

2. What is a pseudopotential and how is it used in optical property calculations?

A pseudopotential is a mathematical construct used to simplify the description of the interactions between electrons and nuclei in a material. In optical property calculations, pseudopotentials can be used to reduce the computational cost and increase the efficiency of DFT calculations by replacing the core electrons with a simpler potential, while still accurately capturing the behavior of the valence electrons.

3. What is plasma frequency and how does it affect optical properties?

The plasma frequency is the frequency at which a material's free electrons oscillate in response to an applied electric field. It is a key parameter in determining the optical properties of a material, as it can affect its refractive index and absorption coefficient. Materials with a higher plasma frequency tend to have higher reflectivity and lower transparency.

4. How is the transmission of light related to a material's optical properties?

The transmission of light through a material is directly related to its optical properties, specifically its absorption coefficient and refractive index. The absorption coefficient determines how much light is absorbed as it passes through the material, while the refractive index determines the speed at which light travels through the material. A higher refractive index typically leads to a slower speed of light and a higher likelihood of absorption.

5. Can optical properties be controlled and manipulated?

Yes, optical properties can be controlled and manipulated through various means such as changing the material's composition, structure, or external environment. For example, the use of dopants or nanostructures can alter a material's optical properties, and the application of an external electric or magnetic field can also affect its behavior. This is a key area of research in fields such as photonics and optoelectronics.

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