Ab initio study of structural, opto-electronic, elastic, and thermal properties of KZnF3

Abstract

In the present study, a theoretical model of potassium-based zinc perovskite (KZnF3) is investigated via structural, electronic, elastic, mechanical, optical, and thermal properties. In addition, lattice dynamics and effect of pressure variation on structural and electronic properties have also been observed. All said calculations are done within the framework of density functional theory (DFT). To authenticate our work we use several exchange correlation functionals. The calculated structural parameters, including cohesive energy, are in accordance with previous experimental and available theoretical studies. The decrease in lattice constant as well as bond lengths is noted with increase in pressure from 0 to 50 GPa. Electronic properties reveal that this material possess an indirect (R–Γ) bandgap while increase in pressure reveals widening of the bandgap. The elastic and mechanical properties show that (KZnF3) is mechanically stable in the cubic phase with predominantly ionic character. The evaluated optical responses of the KZnF3 compound are studied in terms of imaginary and the real parts of the dielectric function ε(ω), refractive index n(ω), reflectivity R(ω), and absorption coefficient α(ω). All of the optical parameters are in good accordance with electronic aspects. Finally, several thermal parameters are calculated, such as unit cell volume, entropy, and heat capacity (Cv) using the quasi-harmonic Debye model.