Modelling tunnelling effects in multidimensional quasiclassical trajectories. Application to the O(3P) + H2 reaction

A new practical approach to model tunnelling effects in quasiclassical trajectories is presented. The proposed method only requires the knowledge of the minimum energy pathway and is independent of the dimensionality of the problem. This approach uses the quasiclassical trajectory to locate the starting tunnelling point and avoids the definition of a tunnelling path. The tunnelling probability is computed as an average over WKB semiclassical probabilities for different possible pathways. Test results on the O(3P) + H2 reaction present a good agreement with quantum results on the same potential energy surface.