Theoretical Studies of Intramolecular and Fragmentation Dynamics of van der Waals Molecules and Clusters

点击翻译按钮获取中文摘要

In this project in the Theoretical and Computational Chemistry Subprogram of the Physical Chemistry Program, Gray will study the intramolecular and fragmention dynamics of van der Waals (vdW) molecules and clusters. The dynamics of vdW systems have received much attention recently because supersonic jet, molecular beam and laser technology have permitted the intimate details of these reactions to be carefully probed. The payoff has often been the observation of fascinating dynamics including mode specificity. This research is aimed at a theoretical understanding of vdW dynamics using recently developed ideas and techniques from nonlinear dynamics, and at developing and extending simpler statistical theoretical approaches to vdW reaction dynamics. One conjecture of this research is that nonlinear resonances between vibrational and/or rotational modes, and phase space bottlenecks to energy flow and chemical reactivity play a significant and unifying role in understanding lifetimes and product distributions. A variety of nonlinear dynamics ideas and methods -- including, for example, simple phase space projections and local estimates of frequencies and exponential separations -- will be applied to each system of interest to explore such possibilities. An alternative RRKM theory -- essentially a novel transition state theory of unimolecular reactions -- will be developed into a useful tool for estimating vdW reaction rates. This involves constructing analytical and intuitive approximations to the phase space bottlenecks which turn out to be the correct transition states required by the theory. The above program of research will be achieved by studying in detail several experimentally relevant and rather different vdW systems, all involving three or more degrees of freedom: NeCl2, ArHD and hydrogen bonded clusters of HF.