[Formula Presented] [Formula Presented] and [Formula Presented]-wave resonances in positronium–lithium-atom scattering

We investigate ortho-positronium–lithium-atom (Ps-Li) scattering using static-exchange and three-Ps-state coupled-channel calculations. The present three-Ps-state scheme, while closely agreeing with the resonance and binding energies in the Ps-H system, predicts [Formula Presented] [Formula Presented] and [Formula Presented]-wave resonances at 4.25 eV, 4.9 eV, and 5.25 eV, respectively, in the electronic spin-singlet channel of Ps-Li scattering. The present calculation also yields a Ps-Li binding in this attractive singlet channel with an approximate binding energy of 0.218 eV, which is in adherence with the recent findings of a chemically stable PsLi system using stocastic variational and quantum Monte Carlo calculations. We further report elastic, [Formula Presented] and [Formula Presented]-excitation cross sections at low to medium energies (0.068–30 eV). © 1999 The American Physical Society.