Abstract: MATH/CHEM/COMP 2002, Dubrovnik, June 24-29, 2002

On Characterization of

Molecular complexity

Milan Randic¹ and Dejan Plavsic²

¹Department of Mathematics and Computer Science, Drake University, Des Moines, Iowa 50311, USA

²Rudjer Boskovic Institute, POB 180, HR-10002 Zagreb, Croatia

We put forward a novel index of molecular complexity, x, taking into account the symmetry of a molecular graph and the specificity of structural components considered. The x index is defined as the sum of augmented valences of all mutually nonequivalent vertices in a molecular graph. The augmented valence of a vertex in a graph is the sum of its valence and valences of all neighboring vertices with the weight 1/2^d depending on their distance, d, from the vertex. The x index is examined on the set of octane isomers and some special classes of graphs. It is also compared with a certain number of alternative complexity measures considered in the literature.