With this grant in the Theoretical and Computational Program of the Chemistry Division, professor Hase will use computer simulation to study chemical dynamics at a microscopic level. The results of these simulations will help experimentalists estimate the rates of important chemical reactions. Different methods will be tested for treating zero point energy in classical trajectory simulations of polyatomic molecules. This will involve, in part, comparisons with quantum dynamical calculations. The theory of unimolecular reaction dynamics will be enhanced by investigating (1) the properties of wave functions and rate constants associated with mode specific decomposition; (2) energy partioning in dissociation products; and (3) the treatment of anharmonicity and vibrational/rotational coupling for microcanonically excited molecules. Microscopic properties of association reactions such as energy transfer pathways and the role of angular momentum will be studied, and an accurate model will be developed for the association rate constant. To bridge the gap between solution and gas-phase chemical kinetics, the association of solvated reactants will be studied. A study of phase space bottlenecks and central barrier recrossing will be performed for SN2 nucleophilic substitution reactions.
