ABSTRACT
The resonance energy, RE, is a rather enduring concept [12] which has served for many years as a theoretical measure of the aromaticity of conjugated systems [87,88]. The RE concept has been the raison d’être for the continuous use of Hfickel theory by organic chemists. For example, many recent developments of Huckel theory were indeed stimulated by a desire to remedy the f^ u re of traditional forms of the theory in predicting the aromatic behaviour of conjugated molecules.
