Theoretical Studies of Dissociative Recombination of Electrons with SH⁺Ions

We are investigating the dissociative recombination (DR) of electrons with the SH⁺ion, i.e. e⁻+ SH⁺ → S + H, in the interstellar medium to improve upon current astrophysical models. In 2017 we addressed the SH(²Π) potential energycurves (PECs) as a DR pathway². We extended this work to investigate alternate DR pathways. Early results suggest that DR through a SH(⁴Π) pathway may resolve the low-energy (< 10 meV) discrepancy between experimentally determined rate coefficients and those determinedthrough the SH(²Π) pathway. Diabatic PECs for the SH(⁴Π) stateswere determined by applying the block diagonalization method to the adiabatic PECs obtained from large active space multi-reference configuration interaction (MRCI) structure calculations³. Rydberg-valencecoupling has proven to be important. Multichannel quantum defect theory (MQDT) is then used to determine the DR cross sections andrate coefficients. The diabatic PECs and preliminary results of the in-progress dynamics calculations will be presented at the conference.