Antiatom-atom scattering with the close-coupling model

Collisions involving atoms and antiatoms have been investigated at low incident energies using close-coupling approximation (CCA). We investigate ortho-positronium-ortho-positronium (o-Ps-o-Ps) scattering up to incident energy 3.4 eV. Antihydrogen-hydrogen elastic scattering has been studied in the energy range 10(-10) to 10(-2) a.u., whereas antihydrogen-helium system has been investigated in the range 10(-16) to 10(-2) a.u. The s-wave elastic scattering parameters, viz., scattering length, effective range, phase shift, cross section etc., have been reported. The present predictions have been compared with the other corresponding theoretical predictions wherever available. Usefulness of CCA model to investigate these systems at thermal energies has been emphasized. (C) 2004 Elsevier B.V. All rights reserved.