An Exact Expression for the Szeged Index of V-Phenylenic Nanotubes and Nanotori

Topological indices of nanotubes and nanotori are numerical descriptors that are derived from graphs of chemical compounds. The Szeged index is one of the most important topological indices defined in physico chemistry. The Szeged index of the graph G is defined as Sz(G) Sigma(uv=e is an element of E(G)) N(u)(e vertical bar G)N(v)(e vertical bar G), where N(u)(e vertical bar G) is the number of vertices of G lying closer to u and N(v)(e vertical bar G) is the number of vertices of G lying closer to v. In this paper, Szeged index of V-phenylenic nanotubes and nanotori, are computed for first time.