Accurate amplitudes for electron-impact ionization from fully correlated wavefunctions

Abstract

Energies near the ionization threshold present a particular challenge for electron-impact ionization calculations. The effect of electron-electron correlation is stronger at lower energies where qualitatively different behavior in the differential cross sections has been predicted. Most of the predictions of the near-threshold behavior have come from semi-classical work. Besides the famous “Wannier threshold law” for the total ionization cross section there are predictions of a flattening of the energy-sharing cross section and a change in shape of the symmetric, co-planar, triply differential cross section. In the case of hydrogen, the near-threshold behavior is expected to be observable within a few eV of threshold. Using the method of exterior complex scaling we can produce accurate wave functions for electron-impact ionization of hydrogen. From these we can extract the complete ionization amplitude. To the extent that comparison is possible, our results agree well with experimental data and the predic...