Electronic Transport Properties Of One-dimensional Quantum Wires In The Two-impurity Model

In this work we take a detail investigation on the electronic transmission properties of a one-dimensional metallic chain with two impurities embedded compactly in it. Some important conclusions are obtained, which are valuable in designing quantum devices.First, we describe the one-dimensional quantum metallic chain with two impurities embedded compactly in it employing a set of energy parameters. They are the site energy of host atoms and impurities, inter-coupling between the two impurity atoms, impurity-lead coupling respectively. Based on single-channel scattering theory, some important physical quantities are analytically calculated via the tight-binding model with the help of the transfer-matrix technique,bound states transmission coefficient and differential density of states are included.Next,We review the conclusions of the single-impurity model to understand the double-impurity model better. Then, the double-impurity model is studied in detail. We consider separately two cases, namely, the symmetric double-impurity model and the antisymmetric double-impurity model with the site energy of two impurities which are equal and opposite respectively. We investigate the following aspects in the two cases: the dependence on the electronic transmission coefficient of the site energy and the inter-coupling and impurity-lead coupling are analyzed in detail. The bound states and differential density of states are also discussed in order to help in the understanding of the transmission coefficient variations. Based on numerical results we found some interesting physical properties for the two impurities problem, some of which are very different from those of one- impurity problem understood before. For example, the relation between transmission coefficient and band states. We also found that the abrupt change in transmission coefficient may occur by increasing the impurity-lead coupling. This characteristic has appealing application potential in designing devices, such as molecular switch. This part is the most important in this paper.Finally, we summary the whole work, and obtain some important conclusions. In addition an idea in designing quantum devices is proposed.