Time-dependent description of charge transport in molecular wires: bottom-up-approach

该项目的主要目标是开发一种新的综合多尺度策略，用于线性分子线中随时间变化的电荷传输模拟。关于模拟技术，这些系统是非常具有挑战性的，因为电荷传输机制取决于链的长度。实验证明了不同长度有机导线在绝热兰道尔型相干隧穿和非绝热马库斯跳穿之间的输运机制。一个一致的理论应该有能力捕捉所有传输机制的转变，这取决于导线长度、热波动和环境影响。因此，基于电子结构粗粒度描述和利用QM/ mm技术处理环境效应以及开放边界条件下稳态非平衡格林函数（NEGF）输运计算的量子动力学方法将被提出并应用于具有代表性的模型型系统。申请人在DFG优先计划SPP 1243的框架内介绍了基本方法。现在，这些技术将迭代交叉连接并进一步发展，以消除现有的不足，并提高有机导线对整个兰道尔-马库斯连续体输运计算的定量预测水平。所开发的技术将应用于基于有机线性链的系统。电线具有以下特点：它们应该是高技术相关性的系统，实验可及性和可重复性，可调长度代表不同的运输制度。为此，本提案中最相关的系统包括低聚物，如低聚（乙烯基乙烯）和（OAE），低聚（乙烯基乙烯）衍生物（OPE）以及pi堆积结构，如DNA和螺旋肽，最近已在其上进行了电荷传输实验。挑战在于再现和量化不同运输制度之间的转变，确定潜在机制并调查可能的应用。

The major goal of the project is to develop a new comprehensive multi-scale strategy for time-dependent simulations of charge transport in linear molecular wires. Regarding simulation techniques these systems are highly challenging since charge transport mechanisms are depending on the chain length. Experimentally transport regimes between adiabatic Landauer-type coherent tunneling and non-adiabatic Marcus-hopping have been proven considering organic wires of varying lengths. A consistent theory should have the ability to capture all transitions in the transport regime depending on the wire length, thermal fluctuations and environmental effects. Therefore, quantum dynamical methods based on a coarse grained description of electronic structure and treating environmental effects by using QM/MM-techniques as well as steady state non-equilibrium Greens Functions (NEGF) transport calculations under open boundary conditions will be advanced and applied to representative model-type systems. The basic methods have been introduced by the applicants within the framework of the DFG Priority Program SPP 1243. Now these techniques will be iteratively cross-connected and developed further to remove existing deficiencies and improve the quantitative predictive level of transport calculations in organic wires towards the whole Landauer-Marcus continuum.The developed techniques will be applied to systems based on organic linear chains resp. wires with the following characteristics: they should be systems of high technological relevance, experimental accessibility and reproducibility, tunable length being representatives for different transport regimes. To this end, the most relevant systems to be included in this proposal are oligomers such as e.g. oligo(aryleneethynylene) and (OAE), oligo(phenylene ethynylene) derivatives (OPE) as well as pi-stacked structures like DNA and helical peptides on which recent charge transport experiments have been performed. The challenge is to reproduce and quantify transitions between different transport regimes, identify the underlying mechanisms and investigate possible applications.