Regularity in chaotic reaction paths II: Ar-6. Energy dependence and visualization of the reaction bottleneck

Reaction trajectories reveal regular behavior in the reactive degree of fre edom and unit transmission coefficients as the system crosses the saddle re gion separating reactants and products. The regularity persists up to moder ately high energies, even when all other degrees of freedom are chaotic. Th is behavior is apparent in a representation obtained by transformation with Lie canonical perturbation theory. The dividing surface in this representa tion is analogous to the conventional dividing surface in the sense that it is the point set for which the reaction coordinate has the constant value it has at the saddle-point singularity. However the nonlinear, full phase-s pace character of the transformation makes the new crossing surface a compl icated, abstract object whose interpretation and visualization, the objecti ve of this paper, can be realized by cataloging the recrossings as they dis appear in successively higher orders of perturbation, and by projection int o spaces of only a few dimensions. The result is a conceptual interpretatio n of how regular behavior persists in a reactive degree of freedom.