Dynamics of (H^-,H₂) collisions: a time-dependent quantum mechanical investigation on a new ab initio potential energy surface

Abstract

A global analytical potential energy surface for the ground state of H₃⁻has been constructed by fitting an analytic function to the ab initio potential energy values computed using coupled cluster singles and doubles with perturbative triples [CCSD(T)] method and Dunning's augmented correlation consistent polarized valence triple zeta basis set. Using this potential energy surface, time-dependent quantum mechanical wave packet calculations were carried out to calculate the reaction probabilities (P^R) for the exchange reaction H⁻+H₂(v,j)→H₂+H⁻, for different initial vibrational (v) and rotational (j) states of H₂, for total angular momentum equal to zero. With increase in v, the number of oscillations in the P^R(E) plot increases and the oscillations become more pronounced. While P^R increases with increase in rotational excitation from j=0 to 1, it decreases with further increase in j to 2 over a wide range of energies. In addition, rotational excitation quenches the oscillations in P^R(E) plots.