First principles calculations of structural, electronic and optical properties of BAs1−xPx alloy

We present first principles calculations of the structural, electronic and optical properties of boron ternary alloy BAs1−xPx, using a hybrid full-potential (linear) augmented plane wave plus local orbitals (L/APW+l0) method within the density-functional theory (DFT). The generalized gradient approximation (GGA) was used as well as the Engel-Vosko GGA formalism to calculate the band gap. We investigated the effect of composition on lattice constants, bulk modulus and band gap. Deviations of the lattice constants from Vegard’s law and the bulk modulus from linear concentration dependence (LCD) were observed for the alloy. Using the approach of Zunger and co-workers, the microscopic origins of the gap bowing were explained. For the optical properties, the compositional dependence of the refractive index and the dielectric constant was studied.