Abstract. The structural formulae of chemical compounds are molecular graphs where vertices represent atoms and edges represent chemical bonds. A kekule structure in a molecular graph is nothing but a perfect matching in the graph. The minimum number of kekule structures that cover the edge set of a molecular graph G is known as the excessive index of G. In this paper we determine the excessive index of the unit cell representation of sodium chloride and 3-D mesh networks representing oxides and selenides of certain chemical compounds. Further we determine the excessive index of hexagonal networks.

Received: October 4, 2012

AMS Subject Classification: 05C70, 05C45

Key Words and Phrases: matching, perfect matching, excessive index, hexagonal networks, 3-D mesh network

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