Topological Reference Systems for the Heterocyclic Conjugated Compound

Abstract

General methods to get propagators under the Huckel approximation are presented for the topological reference systems of the heterocyclic conjugated molecules using the perturbation technique. We reinvestigate the off-diagonal elements of the propagators for the topological reference systems and define a new quantum chemical index for predicting the strength of a bond. Where the topological ref erence systems are the hypothetical reference systems for which construction of all substructural details of the systems, except the cycles, should be taken into account. This method enables us to discuss the influences of the heteroatom on the energy stabilization and chemical reactivity of the heterocyclic conjugated systems. Some quantum chemical quantities (such as the total π electron energy, the total π electron density, the index of the bond strength, the self-atom polarizability, and the frontier electron density)of some heterocyclic. conjugated molecules and its topological reference systems are obtained using the practical calculation method.