Theory of Dissociative Recombination ofD3hTriatomic Ions Applied toH3+

We propose a fully quantal description of ${\mathrm{H}}_3^{+}$ dissociative recombination. The new method combines multichannel quantum defect theory, the adiabatic hyperspherical approach, and the techniques of outgoing-wave Siegert pseudostates. The vibrational, rotational, nuclear spin degrees of freedom of the ion, in their full dimensionality, are all taken into account for the first time in any calculation of polyatomic dissociative recombination. Our calculation of the recombination rate confirms that the Jahn-Teller effect is responsible for the large rate in ${\mathrm{H}}_3^{+}$. The resulting theoretical rates for dissociative recombination of ${\mathrm{H}}_3^{+}$ are in good general agreement with experiment.