The scattering of electrons by atomic systems

Abstract

The eigenfunction expansion method is used to describe the scattering of low energy electrons by atoms or ions having any number of incomplete subshells. Hartree Fock wave functions are used to describe the target system and allowance is made for the inclusion of any number of excited electronic configurations in the expansion. The continuum electron wave functions are given as the solutions of coupled integro differential equations with prescribed boundary conditions. Expressions for the photoionisation cross sections are also derived within this approximation. The formalism presented in this thesis uses the technique of angular momentum recoupling which greatly simplifies the evaluation of the potential terms which appear in the equations and the expressions for the photoionisation cross sections. This has enabled us to write, for the first time, a computer program for the calculation of the various electron scattering and photoionisation cross sections for a general atomic system, which requires as input only the Hartree Fock functions for the bound orbitals and the parameters needed to specify the terms to be included in the eigenfunction expansion. A program which calculates the necessary recoupling coefficients for any given expansion is described.