Calculation of ionization within the close-coupling formalism

We present a method for calculation of differential ionization cross sections from theories that use the close-coupling expansion for the total wave function. It is shown how, from a single such calculation, elastic, excitation, and ionization cross sections may be extracted using solely the T-matrix elements arising from solution of the coupled equations. To demonstrate the applicability of this formalism, the convergent close-coupling theory is systematically applied at incident energies of 150--600 eV to the calculation of e-He ionization. Comparison with available measurements is generally very good. {} 1996 The American Physical Society.