Variational formulation of the R matrix method for multichannel scattering

A variational treatment of the R matrix method for multichannel scattering is given, in which basis functions used for expanding the wave function within a boundary radius r0 need not satisfy specific boundary conditions at r0. As an illustration, a simple basis set of monomial functions (rn,n=1,...,N) is used in a two-channel-model problem with long-range potentials. Excellent results are obtained with ten such functions in each channel. © 1973 The American Physical Society.