Internal consistency in positron-hydrogen-scattering calculations

Abstract

Internal consistency in a close-coupling approach to positron-hydrogen scattering is investigated with a particular focus on the potential overlap between the atomic and positronium continua. We present results for total, total ionization, and 1s positronium-formation cross sections for projectile energies up to 100 eV. We show that, irrespective of whether the continuum is treated by one center, or the other, or both, the same cross sections are generally obtained. This is true only if sufficiently large orbital angular momentum is taken in the close-coupling expansion. Furthermore, unitarity of the close-coupling approach ensures convergence of the physically observable cross sections even if the individual components are not convergent.