Molecular Dynamics of the A + BC Reaction in Rare Gas Solution.
CALIFORNIA UNIV SAN DIEGO LA JOLLA DEPT OF CHEMISTRY
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Molecular dynamics are computed of model atom transfers A BC yields AB C in rare gas solvents at liquid densities. We find that the reaction dynamics can be understood in terms of a simple picture which consists of three stages 1 activation of reactants, 2 barrier crossing, and 3 deactivation of products. The effects seen in stages 1 and 3 can be largely interpreted in terms of existing models of energy and phase decay in solution, while the effects seen in stage 2 can be largely interpreted in terms of gas phase A BC barrier crossing dynamics. We find that Transition State Theory is in perfect agreement with the simulations for the 20 and 10 kcalmol barrier reactions and is a very good description for a 5 kcalmol reaction barrier. At low barrier curvature dynamical effects due to the solvent are shown to induce some recrossings of the transition state barrier, thus causing rate constants calculated by simple transition state theory to be slightly too high. A modification of transition state theory, which considers the effect of the time dependent friction of the solvent on the dynamics at the transition state, is shown to predict corrections to the rate constants in very good agreement with the results from the simulations. Keywords Reaction kinetics Trajectories.
- *REACTION KINETICS
- *MOLECULE MOLECULE INTERACTIONS
- *RARE GASES
- MATHEMATICAL MODELS
- TIME DEPENDENCE
- VAPOR PHASES
- POTENTIAL ENERGY
- MOLECULAR PROPERTIES
- Atomic and Molecular Physics and Spectroscopy