# Optical absorption spectra

The optical absorption spectra is obtained by calculating the frequency-dependent dielectric tensors using VASP. It uses independent particle approximation and assumes only vertical interband transitions to obtain the imaginary part of the dielectric tensors. Via the Kramers-Kronig relations the relationship between the dispersions of the real and imaginary parts of the dielectric function can be established. With both the real and imaginary part of the frequency-dependent dielectric tensors, one can calculate the optical absorption coefficient at different photon energies. Our results are validated against the experimental database: <https://refractiveindex.info>

For more information, please see <https://arxiv.org/abs/2209.02918>.


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