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.

分子结（即化学结合到金属或半导体电极的单分子）中的量子传输是实验和理论研究的活跃领域。分子结提供了在纳米尺度上研究非平衡多体量子物理基本方面的可能性，并且在分子电子学领域引起了极大的兴趣。从理论的角度来看，分子连接中运输的定量描述是一个重大挑战。尽管近年来取得了进展，但仍缺乏可应用于分子连接实际模型的非常准确的传输方法。在该项目中，将进一步开发和实施密度矩阵层次方法以用于分子连接的通用模型。这将提供一种方法，显着扩展可通过数值精确方法寻址的系统范围，特别包括具有非绝热耦合和现实势能表面的模型。这对于低频振动非常重要，其中广泛使用的谐波近似通常是无效的，并且对于表现出大幅度运动（例如扭转运动或基于构象变化的分子开关）的系统来说是必不可少的。该方法将用于研究分子连接中各种有趣但迄今为止尚未探索的机制和现象，包括由势能表面的圆锥形相交引起的非绝热效应、具有大幅运动的系统中的非谐振动运动，例如扭转低聚苯撑的运动，以及此类系统中的电流噪声。