In Fig. evolution of the two bonding factors, covalency and ionicity, is shown with the square root of the kinetic exchange to potential energy ratio. In our case, covalency dominates for all values of the ratio, especially when it is maximal and equal to unity. This feature appears naturally as this point corresponds to the separated atoms limit, and this is classical co-valency (a mix of true covalency and atomicity, as we shown in ). What is new in our approach is that instead of decomposing the total energy into kinetic and potential components, we introduce effective parameters J kex and E ef f based on the exact solution of the extended Heitler-London model for the hydrogen molecule. It is also possible to carry out it for more complex molecules, but the analysis may be cumbersome to implement.