Dynamical effects in molecular junctions

加州圣地亚哥大学的Michael Galperin获得了化学系理论、模型和计算方法项目的一项奖励，以开发用于计算分子结中电子传输的非平衡多体方法。 共振和非共振非弹性电子散射都是分子尺度电子学中的关注点，其中单个分子可以在纳米级器件的不同部分之间形成载流桥。 工作的核心是将分子量子态纳入基于Hubbard非平衡绿色函数和量子主方程的输运形式。这允许同时考虑单个分子和电极之间的耦合、光学和等离子体激元激发和散射、电子跃迁和电荷转移以及振动和传热。 这些能力的发展需要来自新兴的实验，如同时测量电导和拉曼散射的分子桥接金属断裂结下施加的电位偏置。 增加一个混合的经典-量子方法允许容纳非绝热分子运动和开关。向越来越小的电子器件的驱动力作为一个限制的情况下，电流通过一个单一的分子，连接到任何一方的引线。 通常，载流设备具有如此多的原子，以至于它们被统计地而不是单独地对待。 如果单个分子形成桥，这不再是可能的，并且该分子的电子和振动运动强烈影响测量的电导和其他性质。 该奖项下的工作开发了一个一致的理论图片加入铅的统计处理和严格的量子处理的连接分子。 该项目需要融合来自几个不同学科的元素，包括量子化学，分子光谱学，传输理论和统计物理学。 将开发研究生和本科生的分子电子学课程，以传统学科课程无法提供的方式提供这些互连。

Michael Galperin of the University of California San Diego is supported by an award from the Theory, Models and Computational Methods program in the Chemistry Division to develop non-equilibrium many-body methods for calculating electron transport in molecular junctions. Both resonant and non-resonant inelastic electron scattering are of concern in molecular-scale electronics where a single molecule may form a current-carrying bridge between different parts of a nanoscale device. At the core of the work is the incorporation of molecular quantum states into transport formalisms based on Hubbard non-equilibrium Green functions and quantum master equations. This allows simultaneous consideration of coupling between a single molecule and electrodes, optical and plasmonic excitation and scattering, electronic transitions and charge transfer, and vibrations and heat transfer. A need for development of these capabilities comes from emerging experiments such as the simultaneous measurement of conductance and Raman scattering for molecules bridging metallic break junctions under an applied potential bias. Addition of a mixed classical-quantum approach allows accommodation of nonadiabatic molecular motion and switching.The drive toward ever-smaller electronic devices has as a limit the case of current traversing a single molecule that is attached to leads on either side. Usually current-carrying devices have so many atoms that they are treated statistically and not individually. If a single molecule forms a bridge this is no longer possible, and the electronic and vibrational motions of this molecule strongly affect the measured conductance and other properties. The work under this award develops a consistent theoretical picture joining the statistical treatment of the leads and the rigorous quantum treatment of the attached molecule. This project requires merging elements from several different disciplines, including quantum chemistry, molecular spectroscopy, transport theory and statistical physics. Molecular electronics courses for graduates and undergraduates will be developed that provide these interconnections in ways that traditional disciplinary courses cannot.