Calculations of positron scattering from atoms and molecules

In recent years the single-center convergent close-coupling (CCC) method has been extended from quasi one- or two-electron atomic targets to atomic targets that contain any number of active electrons. Using this approach calculations have been completed for positron scattering on Boron, Oxygen, Carbon, Fluorine, Neon, and Argon to obtain total, electron-loss, excitation, and elastic cross sections. Estimates for direct ionization and positronium-formation were obtained through application of a complex model potential scaled to the CCC results. For the listed targets, agreement with electron-scattering experiment and positron-scattering theory for several cross sections has been demonstrated at high energies. However, discrepancies exist between different methods at low energies and for the ionization and positronium-formation processes. With the current calculated cross sections, and CCC results for H, a modified IAM-SCAR method is utilised to obtain these same results for molecular targets. These targets include O₂, O₃, CO, C₂, CO₂, H₂O, CH₄, F₂, CF₄, C₂F₆, C₃F₆, C₆F₆, C₃F_8, BH, BF, BF₂, and BF₃. There is generally good agreement between current and previous results for most transitions, particularly at high energies where this approach is expected to be most accurate.