Current issues in nonadiabatic chemistry

Current issues in electronically nonadiabatic chemistry are reviewed. Issues discussed include the following: mixed quantum/classical dynamics and the retention of coherence in the modeling of nonadiabatic processes in extended systems; nonadiabatic interactions at metal surfaces where transitions to large numbers of electronic states are possible; the representation of a nonadiabatic process in terms of adiabatic or diabatic electronic states; nonadiabatic recrossing and its effects on product branching; and spin-forbidden processes including radiationless decay of potential energetic materials and complex-assisted reactions. Discussed in more detail is the impact new computational tools for locating and characterizing surfaces of intersection have had on nonadiabatic chemistry in general and, in particular, on an emerging issue with potentially broad implications, the role of the geometric phase in molecular dynamics.