Reactant-product decoupling approach to state-to-state dynamics calculation for bimolecular reaction and unimolecular fragmentation

The main purpose of the study is to explore a number of computational metho ds to be used in the RPD approach to state-to-state quantum dynamics calcul ation of polyatomic reactions. Specifically, a mixed time-dependent (TD) an d energy-dependent (ED) approach to solve the RPD equations is investigated . In the mixed TD and ED approach, the reactant wavefunction is computed by the method of wavepacket propagation while the product wavefunction is cal culated by energy-dependent methods. As a result, the reactant-product coor dinate transformation only needs to be carried out for the number of energi es at which the state-to-state S-matrix elements are needed, which is advan tageous if state-to-state information at only a few energies are needed. Si milar implementation of the mixed RPD approach is given for calculation of product state distribution in molecular photofragmentation dynamics.