Tunneling ground-state nuclear

Figure 1. An example of ground state nuclear tunneling along the reaction coordinate (R.C.). The reactant well (R) is on the left side and the product well (P) is on the right. The blue and red lines describe a light and a heavy isotope probability function, respectively.

Figure 7. Diagrams of nuclear configuration for H abstractions and cycloadditions to olefins, showing the possible intersections,

Since nuiny processses demonstrate substantial quantum effects of tunneling, wave packet break-up and interference, and, obviously, discrete energy spectra, symmetry induced selection rules, etc., it is clearly desirable to develop meAods by which more complex dynamical problems can be solved quantum mechanically both accurately and efficiently. There is a reciprocity between the number of particles which can be treated quantum mechanically and die number of states of impcxtance. Thus the ground states of many electron systems can be determined as can the bound state (and continuum) dynamics of diatomic molecules. Our focus in this manuscript will be on nuclear dynamics of few particle systems which are not restricted to small amplitude motion. This can encompass vibrational states and isomerizations of triatomic molecules, photodissociation and exchange reactions of triatomic systems, some atom-surface collisions, etc. 

Figure 6.12 Increase in the reaction quantum yield owing to nuclear tunnelling. Thermal activation takes the system over the barrier and across a funnel from the product surface to the ground-state reactant surface, which may take some system back to the reactants. In contrast, nuclear tunnelling places the reactive systems in a region of the product surface beyond the funnel with the reactants, and the systems cannot return to their original sate.

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