Spectroscopic properties and potential energy surfaces for curium hydrides: CmH(2), CmH(2)(+), CmH, and CmH(+)

A relativistic complete active space multiconfigurational self-consistent field followed by multireference singles + doubles configuration interaction computations are carried out on the potential energy surfaces of electronic states of CmH(2) and CmH(2)(+) for the insertion reaction of Cm and Cm(+) into H(2). We have also carried out corresponding computations on several electronic states of CmH and CmH(+). Moreover, multireference relativistic configuration interaction computations including spin-orbit coupling were carried out on 75 electronic states of CmH(+), which were found to be below the 45 000 cm(-1) region. We have computed the first ionization energy of Cm as 5.94 eV in excellent agreement with experimental value of 5.99 eV. Our computations reveal barriers for the insertion of Cm and Cm(+) in their ground electronic states into H(2), but once the barriers are surmounted, both Cm + H(2) and Cm(+) + H(2) form stable products. The potential energy curves of CmH and CmH(+) reveal the existence of several low-lying open-shell excited states with varied Lambda quantum numbers and spin multiplicities. The excited states of these species exhibit intermediate coupling, although the spin-orbit splittings of the (9)Sigma(-) and (8)Sigma(-) ground states of CmH and CmH(+) are small, exhibiting nearly inverted multiplets.