Zahra Sadri Irani - Department of Chemistry, Faculty of Science, Islamic Azad University, Falavarjan Branch, Falavarjan,۸۴۵۱۵-۱۵۵,I.R.Iran,
Asefeh Karbasioun - Department of Mathematics,payame-Noor University, Tehran, Iran,

A topological index is a real number related to a graph. The wiener index is one of the great topological index that It is equal to the sum of distances between all pairs of vertices of the respective graph[1,2].There are good correlations between Wiener index and variety of physico-chemical properties oforganic compounds. So by graph theory we defined G(n) for every molecular graph and compute the wiener index.aLately the wiener index computed for many nanostructure [3-5]. Authers notice to relationship betweenthe Wiener index and the dynamic parameters of the respective molecule. In particular, they establish an approximate linear dependence between and the molecular vibrational energy, resulting in a linearcorrelation between wiener index and the intramolecular energy. Nanojunctions are the set of nanostructure that one nanotube union with three nanotubes (see Fig.1) In the following record ,we compute a frame for the wiener indexofone class of nanojunction.

molecular graph, Wiener index, Nanojunction,vibrational energies