AVOIDED RESONANCE OVERLAPPING BEYOND THE ENERGY INDEPENDENT FORMALISM .1. VIBRATIONAL PREDISSOCIATION

The interaction of overlapping resonances is studied in the case of a vibrational predissociation in a linear molecule. The energy independent approach rests on the neglect of the variation of the coupling elements with the energy in the continuum. It predicts the formation of trapped and short-lived decay modes when resonances overlap, The relevance of this prediction is discussed on the basis of results obtained from two different methods going beyond this energy independent formalism. The first one consists in searching the solutions of the implicit equation derived from the Feshbach partitioning method, taking into account the full energy dependence of the local effective Hamiltonian H-eff(E). The second one is the variational complex coordinate method (CCM), implemented in a discrete variable representation (DVR). The results demonstrate that the energy dependency enhances the trapping effect, The distribution of the resonance energies in the complex plane is different from the prediction of the energy independent formalism, The fast modes are found to be slower than expected. Their position is also completely shifted. The mean width is not constrained by a sum rule which is characteristic of the energy independent approximation. (C) 1995 American Institute of Physics.