First-principles study of structural, elastic, electronic and optical properties of orthorhombic GaPO 4

Abstract

We have performed ab-initio total energy calculations using the plane-wave ultrasoft pseudopotential technique based on the first-principles density-functional theory (DFT) to study structural parameters, mechanical, electronic structure, chemical bonding and optical properties of orthorhombic GaPO 4. The calculated lattice parameters are in agreement with previous experimental work. The independent elastic constants, bulk, shear and Young’s modulus, Poisson coefficient, compressibility and Lamé constants are obtained using Voigt–Reuss–Hill method. Electronic and chemical bonding properties have been studied from the calculations of band structure, density of states and charge densities. Furthermore, in order to clarify the mechanism of optical transitions of orthorhombic GaPO 4, the complex dielectric function, refractive index, extinction coefficient, reflectivity, absorption efficient, loss function and complex conductivity function are calculated.