Propagation method for the solution of the arrangement-channel coupling equations for reactive scattering in three dimensions

We present a new methodology for solving the three-dimensional reactive scattering problem. It is based upon a convenient choice of coordinates with the arrangement channels coupled either by the Fock method or by the wave function component form of arrangement-channel quantum mechanics. The resulting coupled ordinary differential equations are cast in a form suitable for use with standard nonreactive scattering codes. The method involves no matching of solutions from different arrangements and no numerical derivatives, interpolations of multidimensional functions, or nonlocal kernels.