Examples of Nonadiabatic Predissociation

In the adiabatic picture, the electronic coupling matrix element involves the nuclear kinetic energy operator. The wavefunctions for the two adiabatic 2 + states are mixtures of two dominant configurations, 

There are no C d/dR)C2 cross terms because 4 and (j)2 are mutually orthogonal. The matrix elements of the form 

The We(R) function, resulting from a simple two-state interaction, has a Lorentzian form [Eq. (3.3.14)]. For the Nj B C interaction, We(R) has its maximum in an H-region of numerous constructive and destructive interferences between the vibrational wavefunctions. Thus, slight changes in the vibrational functions resulting from isotopic substitution can drastically alter the vibronic matrix element, 

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