Infinite order sudden approximation for reactive scattering within classical mechanics. I. Theory

An infinite order sudden approximation for treating reactive scattering within classical mechanics is presented. It is shown that requiring the conservation of total energy in the subspace formed by applying this approximation is enough to define, for any given set of initial conditions, a unique trajectory which moves from the reagents to the products arrangement channel. A detailed description of how to apply this method for any three-atom reactive system is given.