Decoupling Scheme for a Semiclassical Treatment of Electronic Transition in Atom-Diatom Collisions: Real-Valued Trajectories and Local Analytic Continuation.

摘要

The semiclassical theory of electronically nonadiabatic transitions in atom-diatom collisions is modified by the introduction of a decoupling approach to the nuclear dynamics. The probability of switching surfaces is calculated locally by integrating in the complex plane over a nuclear coordinate which couples most strongly to the electronic transition. A substantial computational simplification results when this approach is implemented. The power of the method lies in the fact that the potential energy surfaces need be analytically continued locally rather than globally. Thus the trajectories can be maintained on the real axis except for the one point where the surfaces are switched. Computational results are presented and discussed for two model collinear nonreactive systems, F + HH and Br + HH. It is shown that when the possibility of an E-V resonant energy transfer exists, the vibrational as well as the electronic degrees of freedom must be treated quantum mechanically. (Author)