The Electronic Structure and Properties of First-Row Transition Metal Oxides.

The chemical and electronic properties of all diatomic 3d transition metal oxides are investigated to further understand their bonding and growing involvement in atmospheric science. High-level CCSD(T) and spin-orbit icMRCI+Q calculations were used to predict the potential energy curves (PECs) for the ground state and the low-lying states for TiO (3Δ), VO (4Σ-), CrO (5Π), MnO (6Σ+), FeO (5Δ), CoO (4Δ), CuO (2Π), and ZnO (1Σ+). The inclusion of spin-orbit effects is critical for the determination of the ground states in FeO and CoO. Vibrational frequencies of each transition metal oxide are also calculated with CCSD(T) and icMRCI+Q. For the vibrational frequency calculations, the performance of using Hartree-Fock and PW91 reference orbitals was evaluated. The use of PW91 reference orbitals was found to provide better agreement with literature values for the vibrational frequencies and aids in property prediction of highly multireference transition metal oxides. The calculated vibrational frequencies are found to be in reasonable agreement with prior experimental and computational results. Bond dissociation energies (BDEs) of these systems were calculated at the Feller-Peterson-Dixon (FPD) level and are 158.5 kcal/mol (ScO), 158.2 kcal/mol (TiO), 150.1 kcal/mol (VO), 106.2 kcal/mol (CrO), 83.6 kcal/mol (MnO), 97.0 kcal/mol (FeO), 91.4 kcal/mol (CoO), 90.8 kcal/mol (NiO), 65.9 kcal/mol (CuO), and 35.6 kcal/mol (ZnO).