CI potential energy curves for three states of RuO2+

Three low-lying states of RuO2+ are analyzed using large-scale configuration interaction (CI) calculations based on multireference wavefunctions. Relativistic effects are included using relativistic effective core potentials and a spin–orbit (SO) CI approach. The ground state is predicted to be a triply bonded system of 0+ (1Σ+) symmetry having a dissociation energy of 83.8 kcal/mol, an equilibrium bond length of 1.55 Å and a vibrational frequency of 1227 cm−1. Two close-lying states (3Φ) and (3Δ) states have dissociation energies, bond lengths and frequencies of 82.2 and 68.5 kcal/mol, 1.83 and 1.90 Å, and 974 and 974 cm−1, respectively. The states differ in energy at their respective minima by 551 and 4777 cm−1.