The evaluation of quantum chemical indices by the method of moments

Abstract

Moments present a convenient mean to describe molecular connectivity. The method of moments has been used to evaluate the total pi-electron energy EPi, the atomic charge Q,, and the free valence index F,, in conjugated molecules. Because of practical reasons, only the moments up to some finite order L can be considered. Generally, the coefficients of the expansion of a property in terms of moments depend on L . In order to avoid this dependence, the expansion in terms of orthogonal polynomials has been used. Validity and convergence properties of such a method has been examined. The method has been also applied to some conjugated polymers.