Ed R. Smith

A general program to calculate atomic continuum processes using the niem method

Abstract This paper describes a set of computer program packages NIEM which enable electron-atom and electron-ion collision cross sections to be calculated for a general atomic system described by LS -coupling. The calculations are based on a non-iterative integral equation method.

Elastic scattering of electrons by atomic oxygen

Calculations of cross sections for elastic scattering of slow electrons by atomic oxygen in the energy range from threshold to 5 eV are in good agreement with experiments by Sunshine et al (1965). The cross sections are obtained in a close coupling calculation in which real and pseudo-states of the atom are included.

APPLICATION OF THE HARRIS--NESBET METHOD TO A DIPOLE COUPLING POTENTIAL.

Abstract Elastic and inelastic cross sections for a two-channel model problem, in which dipole coupling is assumed, are calculated in the Harris-Nesbet method and compared with direct solutions of the Schroedinger equation. Two different coupling potentials are considered, one of which permits exact solution in terms of known functions, while the other requires a numerical solution. Results accurate to 1 % are obtained for a non-degenerate case when a minimum representation for the wavefunction is taken as a combination of Slater orbitals and spherical Bessel and Neumann functions. For a degenerate case, it is found to be necessary to use sinusoidal energy-dependent terms in addition to Slater orbitals for a description of the internal part of the wave function and that, for the external part, only the leading asymptotic term of the spherical Bessel and Neumann functions need be retained.