The Role of Nonadiabatic Coupling in Bond-Selective Dissociations: Two-Dimensional Model Calculations

The photodissociation dynamics of the model CH2XY (X and Y are halogen atoms) molecule was studied using a time-dependent quantum mechanical method in two dimensions. Simple functional forms were employed as two diabatic potential energy surfaces which correspond to the excited states of C–X (n–σ*) and C–Y (n–σ*). Bond selectivity in the photodissociation is quantitatively examined in terms of the coupling strength between the two surfaces. A method to predict the bond selectivity in the photodissociations is also discussed on the basis of the results of ab initio molecular orbital calculations.