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 methods to be used in the RPD approach to state-to-state quantum dynamics calculation of polyatomic reactions. Specifically, a mixed time-dependent (TD) and 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 calculated by energy-dependent methods. As a result, the reactant-product coordinate transformation only needs to be carried out for the number of energies at which the state-to-state S-matrix elements are needed, which is advantageous if state-to-state information at only a few energies are needed. Similar implementation of the mixed RPD approach is given for calculation of product state distribution in molecular photofragmentation dynamics.