Electronic transport of molecular nanowires

Methods based on quantum mechanics are used to obtain the characteristic curves belonging to the density of states (DOS) of a molecular nanowire and to bridge two metallic electrodes. The impact of the electronic structure of molecules and the coupling mechanism of the metallic contacts on these curves are presented for conjugated compounds based on sulfur, also known as oligothiophene. The molecular nanowire is attached to a couple of gold clusters that represent the electrodes. The molecular electronic structure in the wire was modeled via the Atomistic Tool Kit- Virtual Nano Laboratory (ATK-VNL). The density functional theory and the extended Hückel methods were employed to extract the Hamiltonian matrix elements corresponding to these molecules. Moreover, the impact of the number of Au contact atoms on the DOS was investigated through the use of two models, namely two-atom contact at each electrode and three-atom contact at each electrode via the hollow sites of the gold (111) plane. Furthermore, the impact of the number of thiophene rings present in the wire on the conductance characteristics was determined.