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.

分子结是一种单分子与金属或半导体电极的化学结合，其量子输运是一个非常活跃的实验和理论研究领域。分子结为在纳米尺度上研究非平衡多体量子物理提供了可能性，在分子电子学领域引起了极大的兴趣。从理论的角度来看，在分子连接中的运输的定量描述是一个重大的挑战。尽管近年来的进展，有一个非常准确的传输方法，可以应用到现实的模型的分子连接缺乏。在本计画中，密度矩阵层级法将进一步发展，并应用于一般的分子结模型。这将提供一种方法，该方法扩展了可寻址的系统的范围显着的数值精确的方法，包括在特定的模型与非绝热耦合和现实的势能表面。这对于低频振动是重要的，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的系统是必不可少的，例如，扭转运动或基于构象变化的分子开关。该方法将被用来调查各种有趣的，但到目前为止，在很大程度上未探索的机制和现象，包括非绝热效应引起的锥形交叉的势能面，非谐振动运动系统中的大振幅运动，如例如在oligophenylenes的扭转运动，以及在这些类型的系统中的电流噪声的分子结。