Importance of bound-free correlation effects for vibrational excitation of molecules by electron impact: A sensitivity analysis.

Abstract

One of the most interesting, important, and problematic components of interaction potentials for electron-atom and -molecule scattering arises from many-body effects in the near-target region. Such ``core-polarization'' effects are of particular concern for vibrational-excitation calculations, where these short-range bound-free correlation and nonadiabatic velocity-dependent effects have remained resistant to rigorous treatment, being represented instead by approximations or model potentials. In order to provide guidance for assessing such potentials and insight into the nature of these many-electron effects, we have investigated the sensitivity to core polarization of total, momentum-transfer, rotational-excitation, and vibrational-excitation e-${\mathrm{H}}_{2}$ cross sections. The sensitivity analysis for the latter cross section also comments on a long-standing, severe discrepancy [most recently documented in S. J. Buckman et al., Phys. Rev. Lett. 65, 3253 (1990)] between cross sections determined in various crossed-beam experiments and by transport analysis of swarm data for this simplest electron--neutral-molecule system.