Abstract
R-matrix calculations are presented for elastic and rotationally inelastic scattering of positrons from CO at energies below the positronium formation threshold. The calculations are performed within a number of models that represent charge polarisation effects, the rotational motion of the target and the asymptotic potential. The computed total and momentum transfer cross sections are found to vary widely between the different models employed. A comparison is made between the experimental results for this system and the recent calculations of Jain (1986).