R-matrix calculations of low-energy electron scattering by oxygen molecules

The R-matrix method has been used to study the scattering of electrons by oxygen molecules for impact energies in the range from threshold to 15 eV. Electronic excitation cross sections for transitions to the a¹{{{Δ}}}g$, ${b}¹Σg⁺, and ``6 eV'' states of oxygen are presented. Important contributions from a ²Πᵤ resonance, in addition to the well-known ²Πg resonance, are found to significantly modify previous theoretical predictions. Integral elastic-scattering cross sections are also obtained for the first time for a complicated open-shell system using an ab initio method.