Topology and stability of conjugated hydrocarbons: The dependence of total π-electron energy on molecular topology

In spite of the fact that research on the mathematical properties of the total π-electron energy E (as computed by means of the Huckel molecular orbital approximation) started already in the 1940s, many results in this area have been obtained also in the newest times. In 1978 this author published in this journal a review on E. The present article is another review on E, summarizing the progress in the theory of E, achieved since then.