ON THE HARARY INDEX FOR THE CHARACTERIZATION OF CHEMICAL GRAPHS

A novel topological index for the characterization of chemical graphs, derived from the reciprocal distance matrix and named the Harary index in honor of Professor Frank Harary, has been introduced. The Harary index is not a unique molecular descriptor; the smallest pair of the alkane trees with identical Harary indices has been detected in the octane family. The use of the Harary index in the quantitative structure-property relationships is exemplified in modeling physical properties of the C2-C-9 alkanes. In this application, the performance of the Harary index is comparable to the performance of the Wiener number.