NEGF‐HF Method in Molecular Junction Property Calculations
NEGF‐HF Method in Molecular Junction Property Calculations
复制标题
分子连接性能计算中的 NEGF-HF 方法
DOI：
10.1196/annals.1292.003
复制
发表时间：
2003
影响因子：
5.2
通讯作者：
A. Nitzan
中科院分区：
文献类型：
--
作者：
Michael Galperin;A. Nitzan
摘要：电子-电子相互作用是预测分子传导结特性的一个重要问题。准确的处理需要适当考虑结点上的电位分布以及外部电压降下电子结构的变化。另一个重要的一点是将分子视为开放量子系统的必要性。在本文中，我们在哈特里-福克水平（NEGF-HF）的非平衡格林函数形式主义的框架内解决了这些问题，这允许对问题进行自洽的处理。我们应用该方法研究实验观察到的 I-V 曲线中关于含有不同链长的双层烷硫醇双层的 Hg-Au 结中偏压极性的不对称性。该效应的根源被认为是在相反偏压下结的最高占据分子轨道（HOMO）特征的不对称行为，这导致在电压降符号相反的情况下电子穿过结的传输的有效势垒不同。计算出的电位分布显示了具有薄弱环节的结点的类似电容器的性质。
Abstract: Electron‐electron interaction is an essential issue in predicting the properties of a molecular conduction junction. An accurate treatment requires taking proper account of the potential distribution across the junction as well as for the change in electronic structure under the external voltage drop. Another important point is the necessity to treat molecules as open quantum systems. In this paper we address these issues within the framework of the non‐equilibrium Green's function formalism at the Hartree‐Fock level (NEGF‐HF), which permits a self‐consistent treatment of the problem. We apply the method to study the experimentally observed asymmetry in the I‐V curves with respect to polarity of voltage bias in Hg‐Au junctions containing bilayers of alkanethiols of various chain lengths. The origin of the effect is suggested to be the asymmetric behavior of the character of the highest occupied molecular orbital (HOMO) of the junction at opposite biases, which leads to different effective barriers for electron transfer across the junction at opposite signs of the voltage drop. The calculated potential profile shows the capacitor‐like nature for the junction with the weak link.