Theoretical studies of quantum transport in molecular junctions using the density matrix hierarchy method: Nonadiabatic effects, anharmonic vibrations, and current fluctuations

使用密度矩阵层次法对分子结中的量子输运进行理论研究：非绝热效应、非简谐振动和电流涨落

• 批准号: 317069726
• 负责人: Professor Dr. Michael Thoss
• 金额: --
• 依托单位: Arbeitsgruppe Theoretische Festkörperphysik
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2017
• 资助国家: 德国
• 起止时间: 2016-12-31 至 2021-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/317069726?language=en
• 关键词: Theoretical; studies; quantum; transport; molecular

Quantum transport in molecular junctions, that is a single molecule chemically bound to metal or semiconductor electrodes, is an active field of experimental and theoretical research. Molecular junctions provide the possibility to study fundamental aspects of nonequilibrium many-body quantum physics at the nanoscale and have been of great interest in the field of molecular electronics. From the point of view of theory, the quantitative description of transport in molecular junctions represents a significant challenge. Despite the progress in recent years, there is a lack of very accurate transport methods that can be applied to realistic models of molecular junctions. In this project, the density matrix hierarchy method shall be further developed and implemented for a general model of molecular junctions. This will provide a methodology which extends the range of systems addressable by numerically exact methods significantly, including in particular models with nonadiabatic coupling and realistic potential energy surfaces. This is of importance for low-frequency vibrations, where the widely used harmonic approximation is often invalid, and is indispensable for systems, which exhibit large amplitude motion such as, for example, torsional motion or molecular switches based on conformational changes. The methodology will be used to investigate a variety of interesting, but so far largely unexplored mechanisms and phenomena in molecular junctions including nonadiabatic effects induced by conical intersection of potential energy surfaces, anharmonic vibrational motion in systems with large amplitude motion, such as for example torsional motion in oligophenylenes, as well as current noise in these type of systems.

分子连接中的量子传输是一种与金属或半导体电极结合的单个分子，是实验和理论研究的活跃场。分子连接提供了研究纳米级非平衡多体量子物理的基本方面的可能性，并且在分子电子领域引起了极大的兴趣。从理论的角度来看，分子连接中传输的定量描述是一个重大挑战。尽管近年来取得了进展，但缺乏非常准确的运输方法，可以应用于分子连接的现实模型。在该项目中，应为分子连接的一般模型进一步开发并实施密度矩阵层次结构方法。这将提供一种方法，该方法可以大大扩展可通过数值精确的方法来解决的系统范围，其中包括具有非绝热耦合和现实势能表面的模型。这对于低频振动至关重要，在低频振动中，广泛使用的谐波近似通常是无效的，对于系统而言，这种振幅是必不可少的，这些系统表现出较大的振幅运动，例如基于构象变化，例如扭转运动或分子开关。该方法将用于研究分子连接中的各种有趣但尚未探索的机制和现象，包括势能表面的锥形相交引起的非绝热效应，具有较大幅度运动的系统中的非谐波振动运动，例如寡原烯基因噪声以及这些类型的噪声中的旋转运动，以及这些类型的噪声。