Dissociative recombination of HCO$^+$

The dissociative recombination (DR) mechanism of the important interstellar ion HCO+ at low electron energies is studied theoretically. Our work suggests that DR is driven through capture into Rydberg states, and that no direct mechanism operates at collision energies below a few eV. Our approach includes accurate quantum chemical calculations, the three-dimensional vibrational dynamics and a treatment of the joint electron-nuclear dynamics is treated using quantum defect theory and a frame transformation approach. Results are presented for the calculated autoionization widths of Rydberg states and the dissociative recombination cross sections, and compared with available experiments.