分子结电学特性的理论研究

在第一性原理的基础上，对共扼分子2-氨基-5-硝基-1，4-二乙炔基-4’，-苯硫醇基苯(2-amino-5-nitro-1,4-diethyny-4’-benzenethiol-benzene)与金表面形成的分子结的电学特性进行了理论研究.利用密度泛函理论计算了该分子及扩展分子的电子结构；讨论了分子与金表面的相互作用，定量地确定了耦合常数，求出了电子的迁移强度；利用弹性散射格林函数法研究了该分子结的伏—安特性.计算结果表明，当外加偏压小于0.9V时分子结存在电流禁区，随着偏压升高，分子结的电导出现平台特 关键词： 化学吸附 分子结 分子电子学

A theoretical study of electrical properties of molecular junction

Basing on first principls, we investigate the electrical properties of a molecular junction consisting of 2-amino-5-nitro-1,4-diethyny-4’-benzenethiol-benzene molecule and gold surface. Density functional theory is employed to obtain the electronic structures of the molecule and the extended molecule. Then we determine the interaction energy between the molecule and the gold surface quantitatively. The elastic Green function method is applied to study its current-voltage properties. Numerical results show that when the external applied bias is lower than 0.9V, there is a current gap. With increasing bias, the conductance of the junction exhibits plateaus. These electrical properties are closely related to the electronic structures of the molecular junction. The extended molecular orbits have great contribution to the charge transport, while localized molecular orbits contributes but little to the current where charge transport takes place by tunneling.