Scattering of Positronium by Atomic Hydrogen

Extensive new calculations, in the coupled-pseudostate formalism, are reported for o-Ps $\left(1s\right)$ scattering by H $\left(1s\right)$ in the energy range 0 to 40 eV. An $S$-wave resonance first predicted by Drachman and Houston [Phys. Rev. A 12, 885 (1975)] is confirmed and new resonances are found in the $P$, $D$, $F$, $G$, and $H$ waves. The cross section for o-Ps $\left(1s\right)$ to p-Ps $\left(1s\right)$ conversion is shown to have significant structure. Results for the total cross section and its components indicate that Ps ionization is the main process at the higher energies. Excitation of the H atom becomes increasingly important above 20 eV.