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.