Abstract:

In this paper, we assume that the interaction of two neighboring units is only through their connected bond, but we do not put any limitation on the form of interaction within each unit itself. Then we discuss quantum chemistry calculations for conjugated molecules containing repeated units and arbitrary terminal group units by means of the method of graph theory and the method of difference equation respectively. The characteristic polynomial of the molecules has been obtained, and the iteration for solving energy and AO coefficients by the method of difference equation has also been given. Lastly, as an application of the methods, the rule of linearity of the homologs may be directly obtained.