To model the change in entropy during the dissociation, we define three data points to fit a sigmoid function: The first point is the equilibrium distance of the complex AB r eq , where we have -T ∆S AB , the second point is at infinite distance, hence, with infinitely separated fragments A and B, where we have -T (S A + S B ), the third point is the distance at which we assume the bond of the fragments AB to be broken, which is the inflection point of the sigmoid r cleave , where the entropy amounts to -1 2 T (∆S A + S B ). Hence, we yield