Spin and orbital ordering in CaMnO3 and LaMnO3: UHF calculations and the Goodenough model

Relative energies from unrestricted Hartree–Fock (UHF) calculations for several spin and orbital orderings in CaMnO3 and LaMnO3 in cubic and tetragonally distorted perovskite structures are rationalised using the Goodenough model. Comparison of relative energies from several calculations leads to an estimate that the antiferromagnetic coupling energy exceeds the ferromagnetic coupling energy per Mn ion by ∼10 meV in both CaMnO3 and LaMnO3.