QUANTUM MECHANICAL BEACI-IVE SCA-ITEIUNG VIA EXCHANGE KERNELS: COMPARISON OF GRID VEIWdJS BASIS SET EXPANSION OF Ti-IE EXCHANGE INTERACTION

In the approach to quantum mechanical reactive scattering that we have been pursuing in an earlier paper, the reactive coupling has been described by a non-local exchange interaction in a coupled-channel S&r&linger equation. The results of systematic studies undertaken to identify the most efficient way to include the exchange interaction to infinite order, i.e. exactly, are reported. We find that the grid method used previously by Dardi et al. can be made much more efficient by using gaussian quadrature grids, but that still more efficient is an expansion of the exchange operator in a set of smooth basis functions via the “inner projection” approach of Adams and Miller. Test problems studied are the collinear H + D, , D + HZ, and F + Hz reactions.