Level Pattern Indexes (LPI) of mols. are defined as a sequence of nos. of bonding, nonbonding and antibonding MOs, which are of importance for predicting the stabilities and valence states of the mols. In this paper, a graphical approach is proposed for the evaluation of LPI. It is based on the Syvester law of inertia of linear algebra and the partition technique to reduce the adjacency matrixes into smaller blocks, substantially facilitating the treatment without working out the sequence of energy levels. Applications are focused on nonalternants, polyhedral cages and isomers of C60 with tabulation of LPI which presents some insights into the relationship between mol. behaviors and topol. structures.

Key words: CALCULATION, CHEMICAL BONDS, MOLECULAR ORBITAL THEORY, MOLECULAR ENERGY LEVELS, GROUND STATE, REDUCTION THEORY, ENERGY GAP