S22-S26 in the Supporting Information), stemming from single bonds which are comparable to the one found in regular alkanes, yet weaker than what expected by QM theory. The opposite is true for double bonds, where GAFF's higher barriers indicate too stiff coordinates, comparable to standard double bonds in olefins. This results in a overestimated BLA, is in contrast with expectations based on electronic nature of the polyene system, which are instead correctly described at QM level and, therefore, in the QMD-FF.