Independent-particle-model study of electrons elastically scattering from oxygen

The independent-particle model of Green, Sellin, and Zachor is adjusted to describe the inner and singly excited states of neutral oxygen. It is found that the entire spectrum can be fitted using only two parameters. With the addition of a polarization potential, the ground state of ${\mathrm{O}}^{-}$ is also fitted with a Green-Sellin-Zachor independent-particle model. Low-energy elastic cross sections for electrons on neutral oxygen are then obtained. The calculated cross section fit the data reasonably well. The neutral-oxygen calculations are then extrapolated to zero energy using modified effective-range theory from which we obtain a scattering length of $0.485a_0$. At higher energies, the results of partial-wave calculations are compared to a two-parameter analytic Born approximation.