DFT-study of the energetics of perovskite-type oxides LaMO3 (M = Sc–Cu)

Abstract

The generalized gradient approximation to density functional theory is benchmarked for the calculation of formation enthalpies of lanthanide perovskite-type oxides LaMO₃ (M = Sc–Cu). Three different reaction pathways (from elements, mono and sesquioxides) have been investigated and the systematic errors associated with electron correlation due to overbinding of the oxygen molecule, electron self-interaction within localized 3d states, and geometrical relaxations are analyzed by critical comparison with a large number of experimental data. Calculated formation enthalpies from elements and sesquioxides are in good agreement with experiment when the overbinding of O₂ is corrected for using the Wang ad hoc factor of 131 kJ mol⁻¹ O₂. By contrast, the calculated formation enthalpies from monoxides are systematically too low which are attributable to strong self-interactions due to localized 3d states in MO. The effects of relaxation and choice of magnetic structure on the enthalpies of formation are analyzed.