Department of Physical Chemistry, University of Vienna, Sensengasse 8/7, A-1090 Vienna, Austria.
J Chem Phys. 2011 Oct 21;135(15):154109. doi: 10.1063/1.3653790.
Asymmetric line shapes can occur in the transmission function describing electron transport in the vicinity of a minimum caused by quantum interference effects. Such asymmetry can be used to increase the thermoelectric efficiency of molecular junctions. So far, however, asymmetric line shapes have been only empirically found for just a few rather complex organic molecules where the origins of the line shapes relation to molecular structure were not resolved. In the present, work we introduce a method to analyze the structure dependence of the asymmetry of interference dips from simple two site tight-binding models, where one site corresponds to a molecular π orbital of the wire and the other to an atomic p(z) orbital of a side group, which allows us to characterize analytically the peak shape in terms of just two parameters. We assess our scheme with first-principles electron transport calculations for a variety of t-stub molecules and also address their suitability for thermoelectric applications.
在描述由量子干涉效应引起的最小附近的电子输运的传输函数中，可能会出现不对称线形状。这种不对称性可用于提高分子结的热电器件效率。然而，到目前为止，仅在少数几个非常复杂的有机分子中通过经验发现了不对称线形状，而这些线形状与分子结构的关系的起源尚未解决。在目前的工作中，我们引入了一种分析简单二位点紧束缚模型中干涉峰不对称性的结构依赖性的方法，其中一个位点对应于线的分子π轨道，另一个位点对应于侧基的原子 p(z)轨道，这使我们能够仅用两个参数来分析峰形状。我们使用各种 t- stub 分子的第一性原理电子输运计算来评估我们的方案，并探讨它们在热电器件应用中的适用性。
