The Effect of Hydrostatic Pressure on the Electronic and Optical Properties of GaAs

In this research, the effect of hydrostatic pressure on the electronic structure and optical properties of GaAs compound has been investigated. The calculations have been done based on the density functional theory (DFT) using WIEN2K computational package. This computational package solves Kohn-Sham equations by the full-potential linearized augmented plane wave (FP-LAPW) method self-consistently. The exchange-correlation potential is calculated by the Generalized gradient approximation (GGA) and a combination of modified Becke — Johnson plus local-density approximation (mBJ-LDA) functional. All the electronic and optical properties calculations have been done in the presence of spin-orbit interaction. In the case of electronic structure calculations, using the band structure calculations at different pressures, the pressure dependence of band gap energy is calculated. The results of calculations show that by increasing the pressure the band gap energy increases linearly. Regarding the optical properties, the effect of hydrostatic pressure on the real and imaginary parts of the dielectric function ε(ω) is calculated. The results show that by increasing pressure the absorption edge and the major peaks in the imaginary part of the dielectric function are shifted towards higher energies whereas by decreasing the pressure they are shifted towards lower energies. The results also show that by increasing the pressure, the static dielectric function decreases linearly. Using the results of the real and imaginary dielectric function calculations, the optical gap and the static refractive index at different pressures are also calculated.