Minimum-energy path for the S⁺+H₂→ SH⁺(³Σ⁻) + H(²S) reaction considering the quartet and doublet states correlating to the SH⁺(³Σ⁻) asymptote. The abscissa is the reaction coordinate, defined as the difference of the H₂ and SH distances, R_H2 and R_SH, respectively, in Å. The potential energies displayed correspond to the minimum of energy in the remaining two internal coordinates, i.e., the angle between the H–H and S–H bonds and the coordinate defined as (R_H2 + R_SH)/2. At distances of 6 Å, the interaction energy is lower than 1 meV, and cannot be appreciated in the figure.