A DFT Approach on the Impact of Hydrostatic Pressure on the Structural, Mechanical, Lattice dynamics, and Optical Characteristics of the Cubic Perovskite RbTaO3

Abstract

The structural, mechanical, electrical, lattice dynamic, and optical features of the cubic perovskite RbTaO3 beneath pressure (0150GPa) are scrutinized using ab-initio calculations established on the spin-polarized density functional theory (SP-DFT). In accordance with the lattice parameter-energy variation curve, the compound is none ferromagnetic nor non-magnetic. Mechanical stability criteria for cubic structures disclose that the material is both brittle and stable. In agreement with the Zener anisotropy factor data, the compound displays anisotropic performance between 0 and 40 GPa and isotropic performance above 40 GPa. It was also prominent to have a semiconductor character, as seen by the electrical band structures, and the band gap changed from an indirect one at 0 GPa to a direct one at 150 GPa as a consequence of pressure application. In view of this energy gap transition, RbTaO3 is a likely material for use in photovoltaic, optoelectronic, and photochemical devices. The appearance of negative frequencies in the material makes it dynamically unstable, as can be seen from the phonon dispersion curves. The fundamental optical functions were considered, including the extinction coefficient (), optical conductivity, (), reflectivity (), electron energy-loss spectrum (), absorption coefficient spectrum (), and refractive index (). The optical characteristic indicates that the visible-ultraviolet spectrum is where cubic RbTaO3 is active