Electronic states of Ru2

Abstract
Complete active space multiconfiguration–self-consistent-field (CAS–MCSCF) calculations are carried out on 18 electronic states of ruthenium dimer (Ru2). In addition, multireference singles+doubles configuration interaction calculations which included up to 600 000 configurations are made on the lowest state of Ru2. We find that the 7Δu state is the lowest with re=2.36 Å, ωe=273 cm−1, and De=2.0 eV at the highest level of theory. We find 18 electronic states within ∼2000 cm−1 of the ground state.