Sengul Ozlem, Valli Angelo, Stadler Robert
Institute for Theoretical Physics, Vienna University of Technology, Wiedner Hauptstrasse 8-10, 1040 Vienna, Austria.
Nanoscale. 2021 Oct 21;13(40):17011-17021. doi: 10.1039/d1nr01230d.
Destructive quantum interference (QI) has been a source of interest as a new paradigm for molecular electronics as the electronic conductance is widely dependent on the occurrence or absence of destructive QI effects. In order to interpret experimentally observed transmission features, it is necessary to understand the effects of all components of the junction on electron transport. We perform non-equilibrium Green's function calculations within the framework of density functional theory to assess the structure-function relationship of transport through pyrene molecular junctions with distinct QI properties. The chemical nature of the anchor groups and the electrodes controls the Fermi level alignment, which determines the observability of destructive QI. A thorough analysis allows to disentangle the transmission features arising from the molecule and the electrodes. Interestingly, graphene electrodes introduce features in the low-bias regime, which can either mask or be misinterpreted as QI effects, while instead originating from the topological properties of the edges. Thus, this first principles analysis provides clear indications to guide the interpretation of experimental studies, which cannot be obtained from simple Hückel model calculations.
破坏性量子干涉（QI）作为分子电子学的一种新范式，一直备受关注，因为电子电导广泛依赖于破坏性QI效应的存在与否。为了解释实验观察到的传输特征，有必要了解结的所有组件对电子传输的影响。我们在密度泛函理论框架内进行非平衡格林函数计算，以评估通过具有不同QI特性的芘分子结的传输结构 - 功能关系。锚定基团和电极的化学性质控制费米能级对齐，这决定了破坏性QI的可观测性。全面分析可以区分由分子和电极产生的传输特征。有趣的是，石墨烯电极在低偏置区域引入特征，这可能会掩盖或被误解为QI效应，而实际上源于边缘的拓扑性质。因此，这种第一性原理分析为指导实验研究的解释提供了明确的指示，这是简单的休克尔模型计算无法获得的。
