Parent state swapping of resonances in electron - hydrogen molecule scattering

Ab initio R-matrix scattering calculations are presented for electron - as a function of bond length. It is found that and resonances in the 10 eV region appear to be associated with multiple `parent' target states and that the resonances can swap parents as a function of internuclear separation. It is shown how these phenomena provide an explanation for the inconsistencies in previous assignments of resonances in this region and other anomalies such as pronounced isotopic effects. It is suggested that this parent swapping behaviour is likely to be a common feature of electron-impact excitation of other molecules and is particularly important for any models that include nuclear motion.