Electronic transition, wave packet, nonadiabatic

Since we are interested in electronic phase effects accompanying adiabatic nuclear excursions, and are considering motion near a conical intersection, we must specify the conditions under which adiabaticity obtains. A wave packet moving on one of the excited state potential surfaces will not undergo nonadiabatic transition to the other provided it is further from q = 0 than its width and that... 

An illustration of wave packet propagation on two-coupled electronic states in diabatic representation. Nonadiabatic transition occurs at the intersection region of the two potential energy surfaces, resulting in the observed two portions of the wave packet (initiated on state 1) on the two electronic states, with the larger portion remaining on the initiated state. 

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