The quantum-chemical calculations were performed at the PBE0/def2-TZVP level of theory using the ORCA 5 program package. Each molecule was optimized in the singlet neutral state, and the harmonic frequencies were computed to confirm that the structure found is indeed a local minimum. Then, for each molecule, at the optimized neutral geometry, the energies of the doublet monoanion and polycations up to pentacations were computed. Based on these optimized neutral geometries, the fragmentation products were obtained by breaking the central carboncarbon bonds (see Figure ). The geometries of these products, to reduce computational expenses, were not optimized. In general, this should lead to an underestimation of the dissociation energy in each case of fragmentation. However, our numerical tests for ethylene, trans-1,3-butadiene, and all-trans-1,3,5-hexatriene show that the values obtained with such approximation are well correlated with the adiabatic dissociation energies (see SI sections 1.2 and 1.3 for details).