Reactive Scattering Cross Sections III: Quasiclassical and Semiclassical Methods

Abstract

Classical trajectory methods for calculating inelastic scattering cross sections are covered in earlier chapters of this book, especially Chapters 10 and 12. This chapter covers the extension of this technique to treat reactive scattering. The first question which must be answered in a classical trajectory study of a reactive system is whether one should be using this method at all. Classical trajectory studies are useful not just because they yield reaction cross sections, angular distributions, reactivity as a function of initial and final energy distribution, and other observable reaction at-tributes, but also for the insight they may offer into the actual reaction event. One may look at the atomic motions in representative trajectories, and one may calculate such nonobservables as opacity functions (probability of reaction as a function of impact parameter) and dependence on features of the potential energy surface. But one must be careful not to overinterpret the reaction by a trajectory study. Because many reaction attributes depend sensitively on quantitative and qualitative features of the potential energy surfaces which are not quantitatively understood, one must be cautious about believing that the dynamical details of a particular trajectory calculation are in general accord with reality. Trajectory calculations are discussed from this point of view in Chapter 18 of this book.