SPECTROSCOPIC CONSTANTS AND POTENTIAL-ENERGY CURVES OF 21 ELECTRONIC STATES OF RUH

State-averaged complete-active-space self-consistent-field (SA CASSCF) calculations, followed by first-order configuration interaction (FOCI) and multi-reference singles+doubles CI (MRSDCI) calculations which included up to 100000 configurations, are carried out on 21 electronic states of RuH. In addition spin-orbit effects are investigated using the relativistic CI (RCI) methodology. The ground state of RuH is found to be a X 4Σ- electronic state with Re=1.547 Å, ωe=1938 cm-1 and De=2.9 eV. Many allowed electronic transitions from the ground X 4Σ- state, and from excited 4Π and 4Φ states, are predicted which are yet to be observed. The nature of the low-lying electronic states and bonding in them are analyzed through Mulliken populations, orbital interactions, and the weights of various configurations in the CI wavefunctions. All the low-lying states exhibit ionic character with Ru+H- polarity of bonds. The Ru orbitals in the RuH bonds in the low-ying 4Σ and 4Π states are composed of 43% Ru(s), 4% Ru(p), 53% Ru(d), and 55% Ru(s), 4% Ru(p), and 41% Ru(d), respectively. There is 6.5% and 9% electron transfer from Ru to H in the 4Σ- and 4Π states, respectively. © 1990.