Investigation of electronic and crystalline structure of perovskite crystals

In this study, the review of investigation on electronic and crystalline structure of two well-known perovskite crystals − LaNiO3 and SrRuO3 − is presented. From theoretical perspective, more focus is placed on the density functional theory and its approximations for the solid-state calculations. It is shown that revised functionals substantially improve the description of the crystalline structure for both LaNiO3 and SrRuO3. Concerning the electronic structure, the advantage of the hybrid functionals for reproducing the core level states and the necessity of the spin-orbit interaction for the correct identification of the core level peaks in LaNiO3 are revealed. As for SrRuO3, a strong proof of its weakly correlated nature and oxygen vacancies being responsible for what was previously attributed to the strong electron correlation effects in stoichiometric specimens is provided. The discovery of mechanical instability of tetragonal SrRuO3 and isosymmetric phase transition of orthorhombic SrRuO3 raises new questions about the fundamental nature and technological applications of this material