Nonempirical calculations on diatomic transition metals. II. RHF investigation of lowest closed-shell states of homonuclear 3d transition-metal dimers

Potential-energy curves of the 3d dimer series Sc₂ through Cu₂ are calculated for the lowest closed-shell states within the nonempirical RHF formalism using limited basis sets of minimal to near-double-zeta–plus-polarization size. Calculated spectroscopic constants are compared to semiempirical results as well as to experimental estimates. The possibility for closed- or open-shell ground states is discussed for each dimer. For diatomic Sc and Cu a detailed study of basis set effects on calculated molecular constants is carried out.