Electron scattering from sodium at intermediate energies

A comprehensive comparison is made between theoretical calculations and experimental data for intermediate energy (>or=10 eV) electron scattering from sodium vapour. The theoretical predictions of coupled-channels calculations (including one, two or four channels) do not agree with experimental values of the differential cross sections for elastic scattering or the resonant 3s to 3p excitation. Increasingly more sophisticated calculations, incorporating electron correlations in the target states, and also including core-excited states in the close-coupling expansion, are done at a few selected energies in an attempt to isolate the cause of the discrepancies between theory and experiment. It is found that these more sophisticated calculations give essentially the same results as the two- and four-channel calculations using Hartree-Fock wavefunctions.