Choosing Pseudostates in the Close-Coupling Formalism for the Electron—Atomic-Hydrogen System

A modified close-coupling formalism has been applied to the electron---atomic-hydrogen system. We investigate various possible choices of pseudostates which are used to augment the eigenfunction expansion. As a test of the appropriateness of these choices we have evaluated various bound and scattering properties of the electron---atomic-hydrogen system and have computed photodetachment cross sections for H^- as well. We find that pseudostates which emphasize short-range interactions are superior to those which incorporate long-range polarization effects when one computes elastic scattering phase shifts in the nonresonant region below the $n=2$ threshold. Excellent photodetachment cross sections for H^- are also obtained using initial and final states obtained from a modified close-coupling formalism which includes these short-range pseudostates.