| A simple scheme is proposed to analyze the N-electron wave function obtained in embedded cluster calculations in valence bond terms such as ligand-to-metal charge transfer and non charge transfer determinants. The analysis is based on a unitary transformation of pairs of natural orbitals to optimal atomic-like orbitals. The procedure is applied to compare the degree of ionicity in NiO and MnO, and to explain the existence or absence of Jahn-Teller distortions in LaMnO3, CaMnO3 and CaFeO3. We find that the ground state of LaMnO3 is dominated by non charge transfer configurations, whereas the charge transfer configurations dominate the ground state wave function in the other two perovskites. |
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