Computing fourth atom-bond connectivity index of v-phenylenic nanotubes and nanotori.

Among topological descriptors connectivity topological indices are very important and they have a prominent role in chemistry. One of them is atom-bond connectivity (ABC) index defined as ABC(G)= [formula:see text], in which degree of vertex v denoted by dv . Recently, a new version of atom-bond connectivity (ABC4) index was introduced by M. Ghorbani et.al in 2010 and is defined as ABC4(G)= [formula: see text], where Su = [formula: see text] and NG(u)=[formula: see text]. In this paper we compute this new topological index for v-phenylenic nanotube and nanotori.