Abstract
With their broad range of properties, ABO3 transition metal perovskite oxides have long served as a platform for device applications and as a testing bed for different condensed matter theories. Their insulating character and structural distortions are often ascribed to dynamical electronic correlations within a universal, symmetry-conserving paradigm. This view restricts predictive theory to complex computational schemes, going beyond density functional theory (DFT). Here, we show that, if one allows symmetry-breaking energy-lowering crystal symmetry reductions and electronic instabilities within DFT, one successfully and systematically recovers the trends in the observed band gaps, magnetic moments, type of magnetic and crystallographic ground state, bond disproportionation and ligand hole effects, Mott vs. charge transfer insulator behaviors, and the amplitude of structural deformation modes including Jahn-Teller in low temperature spin-ordered and high temperature disordered paramagnetic phases. We then provide a classification of the four mechanisms of gap formation and establish DFT as a reliable base platform to study the ground state properties in complex oxides.
Highlights
With their broad range of properties, ABO3 transition metal perovskite oxides have long served as a platform for device applications and as a testing bed for different condensed matter theories
We find that the naive density functional theory (DFT) has a higher total energy of 452, 1167, 935, 4313, and 1925 meV/f.u for YTiO3, LaVO3, CaMnO3, LaMnO3, and CaFeO3, respectively
Achieving this requires (a) allowing sufficient structural flexibility in the description of the various phases, so that symmetry breaking reduced crystal symmetries that could lift degeneracies and electronic instabilities could occur, should they lower the total energy, and (b) using an exchange-correlation functional in the Kohn-Sham DFT (KS-DFT) that distinguishes occupied from unoccupied states and minimizes the delocalization error[37]
Summary
With their broad range of properties, ABO3 transition metal perovskite oxides have long served as a platform for device applications and as a testing bed for different condensed matter theories. Achieving this requires (a) allowing sufficient structural flexibility (a polymorphous description) in the description of the various phases, so that symmetry breaking reduced crystal symmetries that could lift degeneracies (octahedral rotations, Jahn–Teller, and bond disproportionation effects) and electronic instabilities could occur, should they lower the total energy, and (b) using an exchange-correlation functional in the Kohn-Sham DFT (KS-DFT) that distinguishes occupied from unoccupied states (such as DFT + U; self-interaction corrected functionals) and minimizes the delocalization error[37].
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