Theoretical Studies of Dissociative Recombination of Electrons with SH$^+$ Ions

We are investigating the dissociative recombination (DR) of electrons with the molecular ion SH$^+$, i.e. $e^- + \mathrm{SH}^+ \rightarrow \mathrm{S + H}$. SH$^+$ is found in the interstellar medium (ISM), and its chemistry is still not fully understood. Understanding the role of DR of electrons with SH$^+$ will lead to more accurate astrophysical models. Recently we addressed the $^2\Pi$ potential energy curves (PECs) of SH as a DR pathway \footnote{Kashinski, Talbi, Hickman \emph{et al.}, J.\,Chem.\,Phys. \textbf{146}, 204109 (2017)}. We are extending this work to investigate the ground and excited $^4\Pi$ PECs of SH as an alternate DR pathway. Large active-space multi-reference configuration interaction (MRCI) electronic structure calculations were performed using the GAMESS code to obtain the PECs for several values of SH separation. Rydberg-valence coupling has proven to be important. The block diagonalization method was used to disentangle interacting states and form a diabatic representation of the PECs. The status of this ongoing work will be presented at the conference.