Ab initio calculations of autoionizing states using block diagonalization: Collinear diabatic states for dissociative recombination of electrons with N2H+

Abstract Dissociating autoionizing states for dissociative recombination of electrons with N 2 H + have been calculated using block diagonalization. Multi-reference CI calculations for collinear N 2 H and N 2 H + were performed to assess the branching ratio to the product channels. The effects of the strong Rydberg-valence mixing in the N 2 H excited states were disentangled from the changes in the molecular orbitals arising solely from N 2 bond stretching and breaking. The results suggest that N 2 + H should be favored over NH + N , because of the absence of a favorable dissociating state for the N 2 bond breaking.