Structural, mechanical, electronic and thermal properties of KZnF3 and AgZnF3 Perovskites: FP-(L)APW+lo calculations

Abstract This study presents a theoretical prediction of the structural, mechanical, electronic and thermal properties of the zinc-based Perovskites (AgZnF 3 and KZnF 3 ) within the framework of Density Functional Theory (DFT) using All-electron self consistent Full Potential Augmented Plane Waves plus local orbital FP-(L)APW + lo method. To make our work comparable and reliable, several functional were used for the exchange-correlation potential. Also, this study intends to provide a basis and an improvement for updating either the values already predicted by other previous work (by using obsolete functional) or to predict them for the first time. GGA-PBE and GGA-PBEsol were used to predict the structural properties of AgZnF 3 and KZnF 3 Perovskites such as lattice parameter, bulk modulus and its pressure derivative and the cohesive energy. For these properties, the found values are in very good agreement; also those found by GGA-PBEsol are closer to other available previous and experimental results. The electronic properties of these materials are investigated and compared to provide a consolidated prediction by using the modified Becke Johnson potential TB-mBJ with other functional; the values found by this potential are closer to the available proven results and show that these materials exhibit an indirect gap from R to Γ point. The charge densities plot for [110] direction and QTAIM (Quantum Theory of Atoms in Molecules) theory indicate that ionic character is predominate for (K, Ag, Zn) F bonds. Finally, the effect of temperature and pressure on the unit cell volume, the heat capacity C V and entropy were studied using the quasi-harmonic Debye model.