Ab initio and semiempirical calculations of the static potential for electron scattering off the nitrogen molecule

Six calculations, three ab initio and three semiempirical, are presented for the static potential (i.e., the interaction potential energy of an electron with the unperturbed charge distribution) of a nitrogen molecule. The ab initio calculations are Hartree-Fock calculations using contracted Gaussian basis sets capable of yielding wavefunctions (1) near the Hartree-Fock limit, (2) near the sp-limit, and (3) at the minimum basis set level. The semiempirical calculations are all within the INDO formalism. We find that the inclusion of d functions in the ab initia calculations is necessary for an accurate description of the anisotropy of the potential. We also find that the INDO calculations give the correct form of the potential at small electron-molecule separation distances but are poor at large distances.