A Density Functional Theory Insight into Structural, Mechanical, and Optical Properties of Rb₂LiTlF₆ Double Perovskite

Abstract

We applied the density functional theory to systematically investigate the geometrical structure, electronic, mechanical, vibrational and optical properties of double perovskite Rb2LiTlF6 in its cubic phase. To the best of our knowledge, many physical properties of this compound are still not well established or not yet investigated; such as phonon properties, mechanical behavior, thermal properties and so on. In this work, we explored the stability of Rb2LiTlF6 by looking at its thermodynamical behavior through calculation of formation energy, cohesive energy, Goldschmidt tolerance factor and phonon dispersion. We examined its mechanical properties based on various characterization descriptors such as the independent elastic coefficients, bulk, shear and Young’s modulus, ratios such as Pugh and Poisson’s, Kleinnman parameter, Zener anisotropy factor, Debye temperature and melting temperature. Sound velocity in this material was predicted from the values of the bulk and shear modulus obtained. Thermal expansion coefficient at finite temperatures were obtained using the approach of quasi‐harmonic approximation. We also investigated its electronic property using generalized gradient approximation and also hybrid functionals. At a later stage, we explored its optical behavior upon the effect of light excitation using the many body pertubation theory approximation. Having envisioned this material as a wide band gap semiconductor, it can be useful in numerous applications such as designing the top‐cell of tandem photovoltaic configuration, photodetection and light emitting diodes. We strongly believe that this work will provide a helpful guidance for future experimental and theoretical investigations of this material.This article is protected by copyright. All rights reserved.