Elastic collisions and rotational excitation in positron scattering fromCO2molecules

Full quantum calculations are carried out for the elastic (rotationally summed) integral and differential cross sections in low-energy collisions of positrons with rigid rotor ${\mathrm{CO}}_2$ molecules. The interaction includes an expansion of the exact Coulomb potential on a single-center (SCE) and a parameter-free correlation-polarization (${\mathrm{V}}_{\mathrm{CP}}$) potential given in local form via density-functional theory (DFT) with gradient corrections. State-to-state rotationally inelastic cross sections (integral and differential) are also presented and their behavior is discussed in relation to what is known from similar experiments with electrons as projectiles. The agreement found between computed and measured elastic integral cross sections is rather good and confirms the realistic quality of a DFT treatment for short-range dynamical correlation effects.