Theoretical investigation of the dissociation of bridged disilyne

Abstract

The dissociation potential energy surfaces of ground-state bridged disilyne ( 1A 1), the Si 2H 2 global minimum, is investigated using the state-averaged multi-configuration self-consistent field (SA-MCSCF) method. The dissociation energy of bridged disilyne into Si 2 ( 1Δ g+H 2( 1Σ + g) is predicted to be 42 kcal/mol. The very small calculated energy barrier (about 1 kcal/mol) given by the SA-MCSCF calculations disappears at the first-order configuration interaction level of theory. The spin-orbit coupling constant between the lowest 1A 1 and 3B 1 states is estimated to be about 60 cm −1 in the crossing region of their potential energy surfaces.