The asymptotic region of the potential energy surfaces relevant for the O(3P) + SO(X3Σ−) reaction

The potential energy surfaces (PESs) and the spin–orbit couplings for all states of sulfur dioxide correlating with the lowest O(3P) + SO(X3Σ−) asymptote have been calculated in the bond formation region employing correlated electronic wavefunctions. The PESs are found to be strongly anisotropic along the bending coordinate. For linear OS⋯O approach, the Σ states lie below the Π states; for the O⋯OS orientation the Π/Σ ordering is opposite. For perpendicular approaches their A′ components form avoided crossings. The electron spin quantum number is no longer a good quantum number for geometries where the multiplets come close together.