Encounter and Reaction Dynamics on the Potential of Mean Force

Department of Physical Chemistry University of Sydney NSW 2006 Australia 

In a stochastic formulation of bimolecular reactions the reaction is perceived to take place on a multidimensional potential surface under the influence of stochastic forces which mimic the collisions with the bath gas. 

It is usual to treat the separation coordinate R as the reaction coordinate, but this is strictly true only at large separations and fails if internal rearrangements dominate the position of the transition state in the full 

It is often easier to consider the problem of bimolecular reaction rate theory from the perspective of dissociation of the particles, and then to evaluate the recombination rate from the derived dissociation rate using the equilibrium constant. The principal difference between unimolecular and bimolecular reactions is in the treatment of angular momentum J. In unimolecular reactions the transition state is regarded as fixed by the internal coordinates simply because centrifugal effects are small. In bimolecular reactions this is not the case, as is demonstrated by the behaviour of the effective centrifugal potential 

In general, when any set of independent coordinates say by assumption of thermalization, the dynamics on the remaining coordinates occurs on the effective potential 

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ENCOUNTER AND REACTION DYNAMICS ON THE POTENTIAL OF MEAN FORCE... 

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