Substitution of the optimal charges (Equation ) into the dissociation energy (Equation ) would yield the final (and tedious) expression for the minimal energy upon dissociation of the parent P Q+ into fragments "X" and "Y". However, for the hydrocarbons with a persistent sp 2 hybridization of the carbon atoms (discussed in more detail in Section 3), the electronegativities of all the species can be approximated to be the same, i.e., χ P ≈ χ X ≈ χ Y . This simplifies the final equation for the minimal dissociation energy of the parent cation with charge Q into fragments "X" and "Y" to be: