Electron-helium S-wave model benchmark calculations. I. Single ionization and single excitation

Bartlett, P.L. and Stelbovics, A.T. (2010) Electron-helium S-wave model benchmark calculations. I. Single ionization and single excitation. Physical Review A - Atomic, Molecular, and Optical Physics, 81 (2). Article number 022715 .

Abstract

A full four-body implementation of the propagating exterior complex scaling (PECS) method is developed and applied to the electron-impact of helium in an S-wave model. Time-independent solutions to the Schrödinger equation are found numerically in coordinate space over a wide range of energies and used to evaluate total and differential cross sections for a complete set of three- and four-body processes with benchmark precision. With this model we demonstrate the suitability of the PECS method for the complete solution of the full electron-helium system. Here we detail the theoretical and computational development of the four-body PECS method and present results for three-body channels: single excitation and single ionization. Four-body cross sections are presented in the sequel to this article. The calculations reveal structure in the total and energy-differential single-ionization cross sections for excited-state targets that is due to interference from autoionization channels and is evident over a wide range of incident electron energies.