Third stage dynamics calculations

The Dynamics of ElectronicaUy Adiabatic Collisions.— There are three parts to a detailed rate theory of processes occurring in electronically adiabatic collisions. First, the potential describing the molecular interaction must be calculated or estimated. Secondly, the equations of motion have to be solved for individual, fully specified, collisions. Finally, the results of calculations on single collisions must be averaged correctly to yield the required result for example, a reactive cross-section or a detailed rate constant. The procedures for the third stage were outlined in Section 2. In the forward direction, i.e. from o(n ln 6) to ic(T), this averaging presents no problems, but it is the difficulty of reversing this process which makes it impossible to obtain detailed information about the collision dynamics or potential from experimental measurements of thermal rate constants. 

Before developing it, we ought to mention that these two stages — MO s and electronic states — are "static levels of description. They should be followed by a third level which is the dynamical analysis of the behavior of the molecule(s) along the calculated potential energy surfaces. The static surfaces can be expected to predict the nature of many or most possible products. The relative quantum yields, the relative rates, and the possible wavelength dependence of the formation of these products can only be obtained from a dynamical study involving, in particular, a detailed analysis of the "radiationless" jumps between various surfaces. 

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