A reduced-dimensionality quantum model which incorporates the full-dimensional energy of the system: Application to the vibrational predissociation of Cl2–Ne2

Abstract

A reduced-dimensionality quantum model is proposed which incorporates the zero-point energy of the neglected modes in a systematic, natural way. In this model the reduced-dimensionality Hamiltonian is obtained by averaging the exact Hamiltonian over the dependence of the full-dimensional initial state of the neglected modes. The reduced Hamiltonian conserves all the terms of the full Hamiltonian, providing a more flexible description of the couplings between the modes considered explicitly in the model. The model is applied to simulate the vibrational predissociation dynamics of Cl2–Ne2, considering the three stretching modes of the complex. The results are compared to experimental data and to previous calculations using a reduced-dimensionality quantum model and a full-dimensional quantum–classical approach. The Cl2–Ne2 resonance lifetimes obtained agree only qualitatively with the experimental and previously calculated ones. By contrast, the present model predicts more correctly than previous calculations the behavior of the Cl2 fragment vibrational distributions observed experimentally. The applicability of the model is discussed and further refinements are suggested.