Dissociative recombination of electrons with H₂⁺

Cross sections for dissociative recombination (DR) of low-energy electrons with H 2 + have been calculated using the configuration interaction method. Both the direct and indirect mechanisms are included; the many autoionising states that contribute to the indirect mechanism are handled by the independent-resonance approximation. Numerical calculations of the appropriate complex matrix elements for indirect DR indicate that the autoionising states are populated predominantly by a second-order mechanism involving coupling with the dissociating electronic potential. The calculations also show that the real and imaginary parts of the matrix elements are comparable, and they suggest that the interference between the direct and indirect mechanisms is sensitive to the phase of the amplitude for the indirect process. Previous calculations that neglected the real part of these matrix elements observed predominantly destructive interference. The author finds the interference may often be constructive, leading on average to larger cross sections, in closer agreement with experiment.