Two new topological indices based on graph adjacency matrix eigenvalues and eigenvectors

The Estrada topological index EE, based on the eigenvalues of the adjacency matrix, is degenerate for cospectral graphs. By additionally considering the eigenvectors, two new topological indices are devised, which have reduced degeneracy for alkanes or cyclic graphs. Index $R{V}_a$ shows similarity to EE in ordering of alkanes with 8–10 carbon atoms, whereas index $R{V}_b$ is more similar to the average distance-based connectivity (Balaban index J). Inter-correlations between these four topological indices are discussed, indicating which factors have predominant influence.