Trial Wave Functions in the Close-Coupling Approximation

The theoretical and numerical consequences of choosing different trial wave functions in the close-coupling approximation are considered. In particular, calculations are carried out on the scattering of electrons by atomic systems with configurations 1s²2s²2pq, $q=2, 3, 4$, where properly antisymmetrized bound configurations 1s²2s²2pq+1 are mixed with the trial continum wave function. An alternative treatment, which eliminates the need for such bound configurations is presented.