A Comparative Study of the Structural, Electronic, and Optical Properties of GaAs Phases Using Different Exchange-Correlation Functionals

We conducted first-principles calculations using density functional theory (DFT) to explore the structural, electronic, and optical characteristics of gallium arsenide (GaAs) in its wurtzite (WZ), zinc-blende (ZB), and rock-salt (RS) crystalline forms. These studies were carried out employing the full potential-linearized augmented plane wave (FP-LAPW) approach within the Wien2k computational framework. For the exchange-correlation (XC) potentials, we utilized various functionals including the local density approximation (LDA), generalized gradient approximation (PBE), Perdew-Burke-Ernzerhof for solids (PBEsol), modified Becke-Johnson (MBJ), and the strongly constrained and appropriately normed (SCAN) meta-generalized gradient approximation (meta-GGA). These functionals were applied to determine key physical properties such as equilibrium lattice constants, cell volume, bulk modulus, pressure derivatives, and energy band gaps. Additionally, we assessed optical features including dielectric and loss functions, refractive and extinction indices, and optical conductivity across the WZ, ZB, and RS phases. Our findings indicate that the structural and optical parameters derived from the SCAN meta-GGA functional show remarkable consistency with experimental observations, although it tends to underestimate the energy band gap. The most accurate predictions for the energy gap were achieved using the MBJ-PBEsol approach, aligning closely with experimental data.