Bijan Taeri - Associate Professor of Mathematics Department of Mathematical Sciences, Isfahan University of Technology, Isfahan, Iran
Abbad Heydari - ph.D Candidate of Mathamtics Department of Mathematical Sciences, Isfahan University of Technology, Isfahan, Iran

A C4Cs net is a trivalent decoration made by alternating squares C4 and octagons C8. It can cover either a cylinder or a torus. Such a covering can be derived from a square net by the leapfrog operation. Topological index is a real number related to a molecular graph. It must be a structural invariant, i.e., it does not depend on the labelling or the pictorial representation of a graph. Wiener index which is the most studied topological index is equal to the sum of all shortest carbon carbon bond paths in a molecule. In this paper we compute the Wiener index of C4C8 nanotubes by finding the distances between all vertices of the graph i.e. the distance matrix. As a corollary of this method we also compute the Schultz (Molecular topological) index of TUC4C8(R) and TUC4Cs(S) nanotubes.

Topological indices-Wiener index- Schultz index-Nanotubes