ELASTIC COLLISIONS AND ROTATIONAL-EXCITATION IN POSITRON SCATTERING FROM CO2 MOLECULES

Full quantum calculations are carried out for the elastic (rotationall y summed) integral and differential cross sections in low-energy colli sions of positrons with rigid rotor CO2 molecules. The interaction inc ludes an expansion of the exact Coulomb potential on a single-center ( SCE) and a parameter-free correlation-polarization (V-CP) potential gi ven in local form via density-functional theory (DFT) with gradient co rrections. State-to-state rotationally inelastic cross sections (integ ral and differential) are also presented and their behavior is discuss ed in relation to what is known from similar experiments with electron s as projectiles. The agreement found between computed and measured el astic integral cross sections is rather good and confirms the realisti c quality of a DFT treatment for short-range dynamical correlation eff ects.