Ab initio Modeling of Elastic and Optical Properties of Sb and Bi Sesquioxides

First-principle calculations performed the structural, mechanical, electronic, and optical properties of Sb₂O₃ and Bi₂O₃ compounds in monoclinic (claudetite and α-Bi₂O₃) and orthorhombic (valentinite) structures. Local density approximation has been used for modeling exchange-correlation effects. The lattice parameters, bulk modulus, and the first derivate of bulk modulus (to fit to the Murnaghan's equation of state) of considered compounds have been calculated. The second-order elastic constants have been calculated, and the other related quantities have also been estimated in the present work. The electronic bands structures and the partial densities of states corresponding to the band structures are presented and analyzed. The real and imaginary parts of dielectric functions and energy-loss function are calculated. Our structural estimation and some other results are in agreement with the available experimental and theoretical data.