Ability of monocentric close-coupling expansions to describe ionization in atomic collisions

We elicit the ability of monocentric close-coupling expansions to describe ionization in p̄+H(1s) collisions. We show that expansions in terms of exponentially decaying basis functions are definitively unable to provide reliable ionizing distributions in the outgoing part of the collision, since they cannot be enlarged enough to suitably reproduce the outer part of the continuum wave functions. We review the construction of a monocentric expansion in terms of spherical Bessel functions confined in a box that has recently been proposed to better describe the ionizing wave functions and hence overcome the failure of the usual expansions [B. Pons, Phys. Rev. Lett. 84, 4569 (2000)]. We ascertain the reliability of the method and enlarge our previous study of ionizing p̄+H(1s) collisions from low to high impact velocities.