Theoretical Studies of Dissociative Recombination of Electrons with $\mathrm{N_2H}^+$ Ions

We are currently investigating the dissociative recombination (DR) of electrons with the molecular ion $\mathrm{N}_2\mathrm{H}^+$. The ion exists in the interstellar medium, and accurate DR rate constants are needed for astrophysical models. We are performing large scale electronic structure calculations of the excited-state potential surfaces of $\mathrm{N}_2\mathrm{H}$ necessary to treat the process $e^- + \mathrm{N}_2\mathrm{H}^+ \rightarrow \mathrm{N}_2 + \mathrm{H}$. The work is based on using the block diagonalization method to determine diabatic potential surfaces. The dissociating surface that governs DR is then is identified, and off-diagonal coupling terms can be used to determine the autoionization width $\Gamma$ that is essential for a dynamics calculation. The surface has been calculated for several different values of the NH distance and the NN--H bond angle. Dynamics calculations using the Multi-Configuration Time-Dependent Hartree (MCTDH) method are also underway. The status of these calculations will be presented at the conference.