DFT investigation on the optical properties of 2D-CaSe

The present work reports a detail density functional study on the structure, electronic and optical properties of hexagonal monolayer Calcium Selenide (CaSe). The first principle investigation using the projector augmented wave (PAW) method with PBE functional under density functional theory has been utilized for the entire work. Initially, we have investigated the thermodynamical stability of the monolayer architecture of calcium selenide through phonon dispersion analysis. Various electronic properties are computed which includes band structure and density of states (DOS). The electronic band structure analysis shows an indirect band gap of 2.96 eV for the monolayer CaSe. The optical properties such as dielectric function, refraction index, reflectivity, absorption spectra and extinction index of the hexagonal monolayer calcium selenide (CaSe) are also investigated in presence of parallel and perpendicular field polarizations. The present observation indicates the anisotropic optical behavior in monolayer CaSe with respect to plane of polarizations (parallel and perpendicular). The smaller value of reflectivity and absorption coefficient indicates the dominancy in the partially visible and ultraviolet energy range which indicates that the material is transparent in this range thus may be used as anti-reflection coating material.