First principles investigation of the structural, electronic, optical and elastic properties of [formula omitted]alloys

Abstract

The structural, electronic, optical and elastic properties of CsCdxPb1−xCl3alloys are studied using the plane-wave pseudopotential method under the framework of density functional theory (DFT). The Perdew–Burke–Ernzerhof functional (GGA−PBE)is employed to treat the exchange and correlation potentials. The supercell approach (SC)and the virtual crystal approximation (VCA)are also used to model the CsCdxPb1−xCl3alloys. Because of the symmetry constraint in the VCAapproach, the calculated lattice parameters of these alloys only within SCapproach show linear behavior in agreement with the Vegard's law. Using the approach of Zunger and co-workers, the microscopic origin of the energy band gap bowing of these alloys is investigated in terms of the volume deformation, charge exchange and structural relaxation. The energy band gap of these alloys is also predicted to be suitable for solar absorber applications. The real and imaginary parts of the macroscopic dielectric function (MDF)of CsCdxPb1−xCl3alloys are studied using the single-particle picture within random phase approximation (RPA). The calculated static dielectric constant of these alloys increases when Cdconcentration decreases. To study the excitonic effects (EXC), the macroscopic dielectric function of these alloys is also calculated through the solution of the Bethe-Salpeter equation (BSE)using Tamm-Dancoff approximation within many-body perturbation theory. The variation of some polycrystalline structural properties of these alloys such as the Bulk modulus, Young's modulus, Poisson's ratio, Pugh's ratio, shear and Zener's anisotropy parameters as a function of the Cdconcentration are studied using perturbation density functional theory (PDFT). The calculated results show that these alloys are mechanically stable and rather elastically anisotropic. This study provides a detailed theoretical analysis of the CsCdxPb1−xCl3alloys and can give helpful guidance for further relevant research.