Microscopic R-matrix theory in a generator coordinate basis. II

The method presented in a previous paper to study heavy-ion scattering is simplified by the introduction of an approximate form of the matrix element over the external region. The approximation does not affect the accuracy but lowers greatly the computational time. Formulae for energies and widths of resonances are also introduced. Results obtained for α-16O scattering are compared with other theoretical results and with experiment. (Auth.)