Department of Physics, University of York, Heslington, York YO10 5DD, United Kingdom.
J Chem Phys. 2012 Feb 14;136(6):064708. doi: 10.1063/1.3684627.
We analyze how functionality could be obtained within single-molecule devices by using a combination of non-equilibrium Green's functions and ab initio calculations to study the inelastic transport properties of single-molecule junctions. First, we apply a full non-equilibrium Green's function technique to a model system with electron-vibration coupling. We show that the features in the inelastic electron tunneling spectra (IETS) of the molecular junctions are virtually independent of the nature of the molecule-lead contacts. Since the contacts are not easily reproducible from one device to another, this is a very useful property. The IETS signal is much more robust versus modifications at the contacts and hence can be used to build functional nanodevices. Second, we consider a realistic model of a organic conjugated molecule. We use ab initio calculations to study how the vibronic properties of the molecule can be controlled by an external electric field which acts as a gate voltage. The control, through the gate voltage, of the vibron frequencies and (more importantly) of the electron-vibron coupling enables the construction of functionality: nonlinear amplification and/or switching is obtained from the IETS signal within a single-molecule device.
我们通过使用非平衡格林函数和从头算计算的组合来分析如何在单分子器件中获得功能，以研究单分子结的非弹性输运性质。首先，我们将全非平衡格林函数技术应用于具有电子-振动耦合的模型系统。我们表明，分子结的非弹性电子隧穿谱（IETS）中的特征实际上与分子-引线接触的性质无关。由于接触不容易从一个器件复制到另一个器件，这是一个非常有用的特性。IETS 信号对接触的修改具有更强的稳健性，因此可以用于构建功能性纳米器件。其次，我们考虑了一个有机共轭分子的实际模型。我们使用从头算计算来研究外部电场如何通过作为栅极电压来控制分子的振子性质。通过栅极电压对振子频率的控制（更重要的是）和电子-振子耦合的控制，使得在单分子器件中构建功能成为可能：从 IETS 信号中获得非线性放大和/或开关。
