Quantum and semiclassical approaches to chemical reaction dynamics.

摘要

In this work, we present methods for studying the dynamics of molecules as they undergo chemical reaction. Methods and applications are presented using two approaches. The first is fully quantum mechanical and as such fully accurate. The second is a semiclassical approach motivated by classical approximations to quantum mechanics.;Within both of these areas one can always extend the utility of the methods by looking for sensible approximations which faithfully represent the chemical dynamics while requiring less effort. A large portion of the present work is devoted to examination and evaluation of such economizing approximations.;In the quantum approach, we examine approximate treatments of angular momentum in the calculation of thermal rate constants. In particular we calculate thermal rates for the reaction O+OH&rlhar2;H+ O2 .;In the semiclassical approach we present several methods aimed at the Monte Carlo evaluation of certain phase space integrals which arise from classical approximations to the Feynman path integral. In these methods quantum dynamics is represented approximately via the interference of many classical trajectories. Here we will examine molecular energy transfer.