Positron-CO scattering below the positronium threshold

The author presents the first calculations on the total cross sections of e + -CO vibrationally elastic scattering in the energy range from 0.25 eV up to the positronium threshold. In the adiabatic-nuclei approximation, a single-centre expansion approach is employed to determine the fully converged scattering parameters. The e + -CO interaction energy is composed of an accurate repulsive static term and a parameter-free attractive correlation-polarisation potential. The results for the total cross sections are compared with recent measurements; the agreement is fair except below 2 eV, where theory underestimates the experimental data by about 50%. Results on the differential, momentum transfer and rotational excitation are also reported in the same energy region.