Comparison of quasiclassical trajectory and classical S-matrix treatments of collinear collisions of F and D2

Abstract

The dynamics of collinear collisions of F with ${\mathrm{D}}_2{\mathrm{(n}}_{\text{\hspace{0.17em}1}}^{\mathrm{\hspace{0.17em}a}}\text{=0)}$ have been studied using standard quasiclassical trajectory and classical S‐matrix (semiclassical) techniques for collision energies ranging from 0.65 to 5.50 kcal mole⁻¹ in the center‐of‐mass system. The results are compared to previous quantum mechanical calculations on the same potential energy surface. At most only three transitions (NR 0→0, R 0→3, and R 0→4) are ``classically allowed'' at any energy studied. Of these, the only transition for which the ``uniform semiclassical'' and quasiclassical results are significantly different is R 0→4. The predicted energy dependence of this transition is discussed in terms of recent experimental determinations of the relative rates of R 0→4 and R 0→3. The ``classically forbidden'' R 0→2 transition is predicted (using the complex‐valued trajectory method) to have a probability which exhibits distinct oscillations as a function of collision energy.