Ab initio calculation of electronic and optical properties of Beryllium Chalcogenides (BeS, BeSe, and BeTe) under the effect of pressure
There are several methods for materials simulation. Ab initio or first principles methods are used to solve the quantum mechanical equation which govern the behavior of a system. Ab initio calculation of the optical and electronic properties of solids is fundamental in solid state physics. APW+lo is used to examine different properties of BeS, BeSe and BeTe. Beryllium compounds show different features in structure under different pressures, and they also show a phase transition from Zinc blende to Hexagonal transitions in II-VI semiconductors. Little is known about the ground state properties of Beryllium Chalcogenides. The aim of this work is to examine the electronical and optical properties of these materials, with the emphasis on their dependence on hydrostatic pressure. First, we calculated the electronic properties such as band structure, charge density, density of state, and the contours of these materials, second we examined their optical properties such as refractive index, the dielectric function (both real and imaginary), and the coefficient of absorption under normal and transient pressure. Two packages: the Wien97 and the Wien2k, are used in our simulation.