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

• Applicants: Professor Dr. Marcus Elstner; Professor Dr. Thomas Frauenheim; Professor Dr. Ulrich Kleinekathöfer
• Subject Area: Theoretical Chemistry: Molecules, Materials, Surfaces
• Term: from 2015 to 2019
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 260747833

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.

• DFG Programme: Research Grants