The molecular topological index is a graph index defined by M T I = sum_(i = 1)^n E_i, where E_i are the components of the vector E = (A + D) d, with A the adjacency matrix, D the graph distance matrix, and d the vector of vertex degrees of a graph. The molecular topological index is well-defined only for connected graphs, being indeterminate for disconnected graphs having isolated nodes and infinity for all other disconnected graphs. Unless otherwise stated, hydrogen atoms are usually ignored in the computation of such indices as organic chemists usually do when they write a benzene ring as a hexagon.

adjacency matrix | degree sequence | graph distance matrix | topological index | vertex degree