On the hyper-Zagreb coindex of some graphs

Abstract

A topological index is a numerical descriptor of a molecule, based on a certain topological feature of the corresponding molecular graph. In this paper some basic mathematical operation for the hyper Zagreb coindices of graph containing the tensor product G1⊗G2, join G1+G2, strong product G1∗G2, disjunction G1∨G2 and symmetric difference G1⊕G2 will be explained. Moreover we studied the expression for the hyper-Zagreb coindex of titania TiO2[n,m] nanotubes and molecular graph of nanotorus have been derived. These explicit formulae can correlate the chemical structure of titania nanotubes and molecular graph of nanotorus to information about their physical structure.