First-passage processes

To place the mfp approach in a broader context, we now extend Eq. 1 to deal more explicitly with the ultimate formation of equilibrated product P [83]. In the case of weak D/A coupling, where a diabatic basis comprised of charge-localized valence-bond structures may be employed to represent the relevant states of the reacting system, the first-passage process can be viewed as the conversion of the activated reactants to the resonant state of activated products (El) subsequently e1 may recross to R (i.e., pass back through the hypersurface in configuration space defining the transition state) or proceed irreversibly to P ... 

S. Redner, A guide to First-Passage Processes, Cambridge University Press, Cambridge, UK,... 

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