SEMI-EMPIRICAL POLARIZATION POTENTIAL FOR LOW-ENERGY POSITRON-ATOM AND POSITRON ATOMIC-ION INTERACTIONS .2. HALOGENS

A previously described model potential for polarization effects in positron-atom interactions is applied to the halogens. The model predicts that (i) each halogen is capable of binding positronium but not a positron, except for iodine, for which the positron affinity has an uncertainty of sign; (ii) no bound excited states for any of the systems exist, except possibly for PsCl; and (iii) the elastic-scattering cross section of positrons off fluorine has a deep Ramsauer minimum at a positron incident energy of about 0.85 eV, as does neon. For (i) results are in substantial agreement with the self-consistent-field results of Cade and Farazdel as corrected for correlation. © 1979 The American Physical Society.