Positron scattering by the negative hydrogen ion

Results are presented for e(+) scattering by H- in the impact energy range 0less than or equal toE(0)less than or equal to10 eV. These include integrated cross sections for Ps formation in the 1s, 2s, and 2p states, as well as in an aggregate of states with ngreater than or equal to3, and for direct ionization. Differential cross sections for Ps formation in the 1s, 2s, and 2p states are also exhibited. The calculations are based on a coupled pseudostate approach employing 19 Ps pseudostates centered on the e(+). It is found that Ps formation in the 2p state dominates that in the 1s or 2s states below 8 eV, that formation in states with ngreater than or equal to3 exceeds the sum of the n=1 and n=2 cross sections above 2.5 eV, and that direct ionization outstrips total Ps formation above 6.3 eV. The threshold law (E-0-->0) for exothermic Ps formation, which includes the cases Ps(1s), Ps(2s), and Ps(2p), is shown to be 1/E-0.