A new application of absorbing boundary conditions for computing collinear quantum reactive scattering matrix elements

Scattering matrix (S-matrix) elements are calculated using absorbing boundary conditions (ABC) together with the channel packet method (CPM). Using the CPM, we compute a time dependent correlation function between reactant and product Mّller states. As the Mّller states evolve in time, they will be attenuated by the ABC which are placed outside the interaction region of the potential. This permits the use of a smaller grid and leads to an order of magnitude improvement in the time required to calculate the correlation function for the H + H2 reaction. The resulting S-matrix elements are in excellent agreement with previous calculations.