Concept of Minimum State Density in the Activated Complex Theory of Bimolecular Reactions *

In some bimolecular reactions, for example, certain low potential-energy barrier reactions, the saddlepoint choice for the position of the activated complex is vague and sometimes incorrect. In these and in some others a different choice is needed. The concept of minimum state density for this purpose, its relation to adiabatic transition state theory and to the maximum free energy criterion, are discussed. It is shown how it may be applied to bimolecular reactions using microcanonical activated complex theory for these reactions.