POTENTIAL-ENERGY SURFACES FOR PT2+H AND PT+H INTERACTIONS

Potential-energy surfaces for ten electronic states of Pt2H as a function of Pt2-H distance are constructed using the complete active space multiconfiguration self-consistent field followed by multireference singles plus doubles configuration interactions which included up to 407 000 configurations. In addition, the spin-orbit effects were included through the relativistic configuration-interaction method. The potential-energy curves of low-lying electronic states of PtH and spectroscopic constants of 11 states of PtH are also computed using the same method. The experimental A′ -X 2 spectroscopic bands of PtH are reassigned to the 2Σ+ (II)-1/2(I) transition. A tentative reassignment of the observed B′-X1 system is also suggested. The ground state of Pt2H is found to be of E(I) symmetry when spin-orbit effects are incorporated with a bridged structure [Re (Pt-Pt) = 2.46 Å, Re (Pt-H) = 1.684 Å]. A very low-lying excited state E(II) (Te = 0.14 eV) was found for Pt2H. The De (Pt2H) = 59 kcal/mol compared to the De (PtH) = 72 kcal/mol, indicating lower stability of the Pt2H bridge compared to PtH diatomic. Some of the low-lying electronic states of PtH, especially 3/2 states, exhibit avoided crossings. © 1990 American Institute of Physics.