Comparison of electron transport in Graphyne ring and benzene using tight-binding model and density functional theory

In this paper, we study the electrical conductance of a molecular bridge consisting of a graphyne ring with the chemical formula C18H6 connected to two cumulene electrodes using the tight-binding model. We then compare its conductance to a similar system in which the graphyne ring has been replaced by a benzene molecule. To do this, we first obtain the structural characteristics of the studied rings using density functional theory, and then use the method of matching levels, to obtain the tight-binding parameters, i.e., the on-site and hopping energies for the benzene and graphyne rings. Using these parameters, we study the electrical conductance for these two molecules, the benzene and the graphyne rings. We conclude that when these two molecules are in the same position between two cumulene electrodes, they exhibit the same electrical properties. However, in the graphyne ring, a phase transition from metal to semiconductor or vice versa can be created with less energy than in a benzene ring.