State-to-state reactive scattering using reactant-product decoupling

In this paper, we review a quantum wave packet method for computing state-to-state quantum dynamics of three-atom and four-atom bimolecular reactions using the reactant-product decoupling (RPD) approach. The long propagation times needed in order to extract state-to-state observables cover geometries at which the fragments are far apart on the reactant and product side of the reaction valley. To alleviate the coordinate problem, we partition the coordinate space into three regions, describing reactants, products and the interaction region each using a basis set optimized for the particular region. The wave packet is propagated simultaneously over all three regions, and it is transferred between the regions using a system of artificial reflecting and absorbing potentials. We review the accuracy and efficiency of the method and comment on its prospects for yielding accurate differential cross sections of four-atom reactions in the near future.