A multireference time-dependent coupled cluster study of the intramolecular vibrational relaxation process

A multireference time-dependent coupled cluster (MRTDCCM) study of the intramolecular vibrational relaxation process in a model hydrocarbon is presented. Two Ansatze, the ordinary exp(S) and the normally ordered exp(S) are used to map the model space component to the exact wavefunction. The survival probability of the initial state and the energy in the CH mode are calculated. It is found that the ordinary MRTDCCM provides a better description than the normally ordered approach for the short-time dynamics.