R-matrix calculations of low-energy electron collisions with methane

Abstract

R-matrix calculations are performed for electron collision with CH4 at energies between 0.02 and 15 eV using a series of different ab initio models for both the target and the full scattering system. A target model similar to the standard multi-reference configuration interaction used in electronic structure calculations is found to give the best results. Results are presented for elastic scattering, with particular emphasis on the Ramsauer-Townsend miminum, and for rotational excitation, momentum transfer and electron impact dissociation. Extensive comparisons are made with previous studies.