Difference between: Absorbance and Absorption Cross section

[khuili]

Hello,
hello, I ask you to tell me the difference between the "absorbance" calculated from the dielectric function, and the "absorption cross section" calculated from Real-time TDDFT. is that they can give the same appearance spectrum?
Thank you very much

 

[eljose79]

.

Hello,

Thank you for your question. The absorbance and absorption cross section are both measures of the amount of light absorbed by a material. However, they are calculated using different methods and therefore can give slightly different results.

The absorbance is calculated from the dielectric function, which is a measure of how a material responds to an electric field. It takes into account the material's electronic structure and can be used to calculate the amount of light absorbed by the material at a specific wavelength. The absorbance is typically measured using spectrophotometry and is often reported in units of absorbance (AU).

On the other hand, the absorption cross section is calculated from Real-time TDDFT (Time-Dependent Density Functional Theory), which is a computational method used to study the electronic structure and dynamics of molecules and materials. The absorption cross section is a measure of how efficiently a material absorbs light at a specific wavelength. It is often reported in units of square meters (m^2).

While both the absorbance and absorption cross section can give similar appearance spectra, they are calculated using different methods and may not always be directly comparable. This is because the dielectric function and Real-time TDDFT take into account different factors and may have different levels of accuracy. Therefore, it is important to consider the specific method used when interpreting the results.

I hope this helps to clarify the difference between absorbance and absorption cross section. Let me know if you have any further questions. Thank you.