Direct Dissociative Recombination and Ion-pair Formation of $\mathrm{HeH}^+$ Isotopologues

Abstract

Direct dissociative recombination and resonant ion-pair formation reactions of $\mathrm{HeH^+}$ are theoretically studied using time-dependant wave-packets methods. The wave packets are propagated on potential energy curves that are in either the adiabatic representation or the diabatic representation. The reaction cross sections are computed for collisions of different isotopes of $\mathrm{He}$ and $\mathrm{H}$. The reactions are modeled in the collision energy range 0 eV to 50 eV. Final states distributions are also investigated for the $\mathrm{^4HeH^+}$ dissociative recombination reaction, showing dominance of contribution from states of $^2\Sigma$ symmetry in the diabatic representation. In the adiabatic representation, the $^2\Pi$ and $^2\Delta$ states dominate at lower collision energies. The resonant ion-pair formation reaction is investigated using two sets of representation for the potential energy curve of the ion-pair state. The results are compared with available experimental and other theoretical results. The present model yields a reaction cross section that is larger than previous results.