Theoretical Investigation of HS2 Radical and Its Positive Ion

Ab initio theory with VQZ (valence quadruple zeta) basis set at the CASSCF (complete active space self consistent field) level was used to predict the shape of the potential energy functions of the HS2 radical and its cation HS2+. In each case, calculations have been carried out for the lowest electronic states for linear and bent geometries. For HS2, the X2A″ ground electronic state correlates in linear geometry with a 2II state. It leads with the A2A′ state to a bent‐bent Renner‐Teller system. For HS2+, the ground electronic state is X3A″ and it correlates with a 3Σ− state. The cuts of potential energy functions along the internal coordinates for all the electronic states correlating with the lowest dissociation asymptotes have been taken into account. This will be very helpful for understanding the reactivity of the S, S+, H, and H+ atomic systems with the SH, SH+, S2 and S2+ diatomic species to form the triatomic HS2 and HS2+ systems, which play a key role as intermediates in sulfur‐bearing species re...