CASSCF/aVTZ optimized reaction paths for the conversion between C₂+S and CS+C, which occurs on several potential energy surfaces of CCS. The reaction coordinate is defined as R_CS−R_CC, while the valence angle, γ_CCS, was held fixed at 179.9° in the geometry optimizations. Five A″ and four A′ electronic states of CCS were considered for each multiplicity: triplet (bottom panel), singlet (middle panel), and quintet (top panel).