A semiclassical model for tunneling from one classically allowed region on a potential energy surface to another is described. The principal feature of this model, compared to earlier (more ‘‘rigorous’’) multidimensional semiclassical tunneling theories, is that it can be implemented in a straightforward way within the framework of a standard classical trajectory simulation. Applications to several examples of unimolecular isomerization and unimolecular dissociation show that the model is capable of providing excellent results over a wide range of conditions (i.e., coupling strengths, different symmetries of couplings, etc.)
REFERENCES
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For a recent survey of classical trajectory methodology and application, see L. M. Raff and D. L. Thompson, in Theory of Chemical Reaction Dynamics, edited by M. Baer (Chemical Rubber, Boca Raton, FL 1985), Vol. III. pp. 1–122.
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Equation (2.2a) is correct for small tunneling probabilities, More generally, one must include a “survival probability” factor, so that Eq. (2.2a)becomes where and for with still given by Eq. (2.2b).
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