Semiempirical polarization potential for low-energy positron-atom and positron-atomic-ion interactions. II. The halogens

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Abstract
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.