A Molecular Orbital Method For Inorganic Molecules: Application to Transition Metal Oxides

Semiempirical approximations for the SCF-Hamiltonian matrix elements in the LCAO-MO framework, similar to those used in the SCCC-MO method, are developed from the appropriate Roothaan equation. The expression for the off-diagonal elements is found, by comparison with minimal basis set SCF-MO computations, to be semiquantitatively accurate, The equation for the diagonal elements is noteworthy because it includes a correction term to account for two-center interactions. A limited application is made to the transition metal diatomic oxides TiO and CuO, where the empirical parameters are derived by fitting the observed ground-state configuration for TiO. Other computed properties are then found to be in reasonable agreement with experiment, more rigorous computations, and intuitive chemical reasoning.