Hindered Rotor States for the Planar H + H2 Reaction

Abstract

A numerical procedure for solving the rotational differential equation for the planar $\mathrm{H}+{\mathrm{H}}_2$ reaction in natural difurcation coordinates is described. The procedure has the advantage that it may be applied uniformly over the entire range of the reaction coordinate. The symmetry of the differential equation is utilized to simplify the form of the wavefunctions, and their asymptotic behavior provides a state labeling criterion. The conditions under which any pair of energy levels may become either identically or nearly degenerate is investigated. It is shown that as the reactants approach the transition state (s=O), the rotational wavefunctions smoothly pass through forms characteristic of free rotation, hindered rotation, and finally of a bending vibration. At s=O, equal probability density is shown to be highly localized at the entrance of each rearrangement channel.