POTENTIAL-ENERGY SURFACES FOR THE INSERTION OF RE AND RE+ INTO H2

Potential energy surfaces of 12 electronic states of ReH2 and 13 electronic states of ReH2+ are computed. Complete active space multiconfiguration self-consistent field (CAS-MCSCF) followed by multireference configuration interaction calculations, which included up to 1.5 million configurations, were carried out on these electronic states of ReH2 and ReH2+. In addition, spin-orbit effects were included using the relativistic configuration interaction (RCI) method. Our computations reveal that the ground states of Re(6S) and Re+ (7S) do not insert into H2 while the excited Re(6D) and Re+ (5G) states insert into H2 spontaneously. The ground state of ReH2 is found to be a high-spin linear 6-SIGMA-g+ state while the ground state of ReH2+ is found to be a bent 5B2 state. There are low-lying bent sextet and quartet minima for ReH2 while there are corresponding triplet and singlet bent minima for ReH2+. The 3B2 and 1B2 bending potential energy surfaces of ReH2+ exhibit double minima attributed to two possible Re(d) hybridizations. The spin-orbit effects were found to be non-negligible for both ReH2 and ReH2+.