A general first-principles theory of dissociative recombination is developed for highly symmetric molecular ions and applied to ${\mathrm{H}}_3{\mathrm{O}}^{+}$ and ${\mathrm{CH}}_3^{+}$, which play an important role in astrophysical, combustion, and laboratory plasma environments. The theoretical cross sections obtained for the dissociative recombination of the two ions are in good agreement with existing experimental data from storage ring experiments.

• Received 20 September 2011

DOI:https://doi.org/10.1103/PhysRevLett.108.023202