Low-energy electron-H₂⁺collisions: variation of resonance parameters with internuclear separation

The positions and widths of all the low-lying Sigma and Pi resonances in the electron-H2+ collision problem are examined as functions of H2+ geometry. The scattering calculations reported are based on the R-matrix method and include both coupled-state and polarisation effects non-empirically. Two- and four-coupled-state calculations are presented. Agreement with many of the previous calculations is found although some published data are found to be in error. Predictions for the 2 Sigma g+ to 2 Sigma u+ electronic excitation cross section are also given.