A theoretical study of the dissociative recombination of SH$^+$ with electrons through the $^2\Pi$ states of SH

TL;DR

This paper presents a detailed theoretical analysis of the dissociative recombination process of SH$^+$ ions with electrons, using advanced quantum chemical calculations and quantum defect theory to compute reaction rates.

Contribution

It introduces a comprehensive computational approach combining multireference configuration interaction and diabatic Hamiltonian construction to accurately model the process.

Findings

Calculated dissociative recombination rates agree with recent experimental data.

Identified key electronic states involved in the recombination process.

Provided detailed potential energy curves for SH$^+$ and SH.

Abstract

A quantitative theoretical study of the dissociative recombination of SH$^+$ with electrons has been carried out. Multireference, configuration interaction calculations were used to determine accurate potential energy curves for SH$^+$ and SH. The block diagonalization method was used to disentangle strongly interacting SH valence and Rydberg states and to construct a diabatic Hamiltonian whose diagonal matrix elements provide the diabatic potential energy curves. The off-diagonal elements are related to the electronic valence-Rydberg couplings. Cross sections and rate coefficients for the dissociative recombination reaction were calculated with a step-wise version of the multichannel quantum defect theory, using the molecular data provided by the block diagonalization method. The calculated rates are compared with the most recent measurements performed on the TSR ion storage ring in Heidelberg, Germany.