Introduction of a novel additivity scheme coincidence with homodesmicity concept for (CH)xNy (x + y=6) molecules

In this study, group additivity corresponding to ab initio derived total electronic energies among all members of triple sets of nitrogen-containing heterocyclic six-membered ring molecules has been investigated by suggesting two additivity schemes. It has been demonstrated that, almost all triple sets conforming to the newly presented additivity scheme have been predicted to be additive. On the contrary, by using the groups (defined as a polyvalent atom in a molecule together with all of its ligands), group additivity of above-mentioned sets cannot be predicted at all. We have introduced “homodesmicity” criterion as a general and more reliable tool than known prerequisite condition of groups conservation to predict existence of group additivity in these molecules. In addition, it has been shown that group additivity is insensitive to the combination of methods and basis sets used to drive the total electronic energies.