Ab initio adiabatic polarization potentials for low-energy electron-molecule and positronmolecule collisions: The $e$-${\mathrm{N}}_2$ and $e$-C${\mathrm{O}}_2$ systems

Most theoretical calculations of cross sections for low-energy electron- and positron-molecule collisions include the important induced-polarization effects in the interaction potential by means of a semiempirical adiabatic approximation based on the known asymptotic form of the potential. In order to examine the validity of the assumptions implicit in this procedure, ab initio adiabatic polarization potentials have been calculated at the self-consistent-field level of accuracy for the $e$-${\mathrm{N}}_2$ and $e$-C${\mathrm{O}}_2$ systems. The resulting potentials deviate from the asymptotic form for intermediate electron positions outside the molecular charge cloud. In addition, the angular dependence of the potentials differs from that assumed in the semiempirical form.