Phosphide in gallium bismuth: structural, electronic, elastic, and optical properties of GaP_xBi_1-x alloys

The structural, electronic, elastic, and optical properties of ternary alloys GaP_xBi_1-x as a function of phosphorus concentration were studied using ab initio calculations. We have used the full-potential linearized augmented plane wave method-based density functional theory. The potentials have been described by the generalized gradient and modified Becke-Johnson approximations. Results on lattice parameters, energy band gap, bulk modulus, elastic, and optical properties are reported. They are in good agreement with available theoretical and experimental data. Moreover, the dependence of structural and electronic properties on the composition has been analyzed. A deviation from linearity is observed for the lattice constant and the bulk modulus. In addition, the elastic constants and moduli were calculated and used to examine the mechanical stability. Both parts of dielectric-function and other optical parameters have been analyzed.