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全面的多尺度策略，用于线性分子线中电荷输运的随时间变化的模拟。关于模拟技术，这些系统极具挑战性，因为电荷传输机制依赖于链长。在实验上，考虑不同长度的有机导线，证明了绝热Landauer型相干隧穿和非绝热Marcus跳跃之间的输运机制。一个一致的理论应该能够捕捉到传输机制中的所有转变，这取决于导线长度、热波动和环境影响。因此，基于电子结构的粗粒度描述和利用QM/MM技术处理环境效应的量子动力学方法以及在开放边界条件下的稳态非平衡格林函数(NEGF)输运计算将被提出并应用于典型的模型类型系统。申请人已在DFG优先方案SPP 1243的框架内介绍了基本方法。现在，这些技术将迭代地交叉连接和进一步发展，以消除现有的不足，提高有机导线输运计算对整个Landauer-Marcus连续体系的定量预测水平。所开发的技术将分别应用于基于有机线性链的系统。具有以下特点的导线：它们应该是具有高度技术相关性、实验可获得性和可重复性的系统，长度可调代表不同的运输制度。为此，本提案中将包括的最相关的体系是低聚物，例如低聚(芳亚乙炔)和(OAE)，低聚(苯乙炔)衍生物(OPE)，以及最近已在其上进行电荷传输实验的pi堆叠结构，如DNA和螺旋肽。挑战是再现和量化不同运输制度之间的过渡，确定潜在的机制，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.