Mehdi Pishahang

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

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.