Unified treatment of resonant and nonresonant mechanisms in dissociative recombination: Benchmark study of CH

The theoretical approach developed here treats uniformly the direct and indirect mechanisms of dissociative recombination (DR) in a diatomic ion. The present theory is based on electron-scattering calculations performed at several internuclear distances in the molecule. It is easy to implement because there is no need to separately evaluate couplings and the bound dissociative states of the neutral molecule. The theory can be applied to molecular ions with or without electronic resonances at low energies. The approach is applied to compute the DR cross section in electron-CH+ collisions. The computed cross section agrees generally well with recent state-resolved data from a cryogenic storage experiment, which validates the approach.

Automated summary

This article presents a new theoretical approach that uniformly treats the direct and indirect mechanisms of dissociative recombination (DR) in a diatomic ion. The approach is based on electron-scattering calculations performed at different internuclear distances in the molecule, and it is easy to implement without the need to separately evaluate couplings and bound dissociative states of the neutral molecule. This approach can be applied to molecular ions with or without electronic resonances at low energies. The computed DR cross section in electron-CH+ collisions agrees well with recent state-resolved data from a cryogenic storage experiment, validating the approach.