Describing paramagnetic phases of ABO₃ transition metal oxide perovskites with Density Functional Theory

ABO₃ oxide perovskites, where B is a transition metal element with partly occupied 3d shells often show in their spin disordered paramagnetic (PM) phases insulating behavior, whereas naïve band theory systematically predicts metallic state. The latter qualitative failure had motivated explicitly correlated theoretical approaches going beyond single determinant DFT approaches.We enquire what is the minimum theoretical description that correctly captures gapped PM phases for open shell systems. Whereas naïve band theory was previously applied to PM phases by assuming zero moment on an atom-by-atom basis (producing incorrectly a non magnetic metal), we permit more flexible unit cells by using the “special quasi-random structure” methodology (where the total moment is zero but local disordered configurations can have moments), and allow energy-lowering symmetry breaking by way of correctly occupying partially filled degenerate levels. We find that DFT can reproduce band gaps of spin-disordered phases for several Mott insulating ABO₃ oxides with different B atom d fillings.