Optical properties of α-Seα-Se revealed by ab initio calculations

Detailed optical functions and optical properties of a α-monoclinicα-monoclinic phase of Selenium (α-Se)(α-Se) are presented over a wide range of angular frequencies ωω by first-principles calculations. An optical band gap of 2.05 eV and a mobility gap of 2.17 eV±0.05 are observed in the present calculations. The imaginary part of the dielectric function has been obtained from the frequency dependent dielectric matrix and the use of the Kramers–Kronig (KK) relation allows us to determine the real part of the dielectric function. Optical functions and optical properties revealed the occurrence of a long range order in Se. For the first time, infrared and absorption spectra of monoclinic-Se were studied using the Kramers–Kronig (KK) relation by ab initio method. Finally, detailed studies of other dielectric related optical constants such as reflectivity, transmission, reflection and absorption coefficients were also presented.