Otherwise, ECT and EPOL terms show low stabilizing contributions in the non-covalent complexes because they are mainly short-range terms. Specifically, ECT shows a slightly larger contribution than EPOL, with a contribution of up to 18% (Phos-C50). ECT contribution in these cases relates to the donor-acceptor orbital interactions as noted above: donation 3p(Phos)→*C-C(Fullerene), and back-donation 2p(Fullerene)→*P-P(Phos). In this way, ECT contributions decrease as the number of transferred electrons decreases.