BITT - Bremen Initiative on Time-dependent Transport: Atomistic approaches towards photo-induced quantum transport dynamics across single molecules

• Antragsteller: Professor Dr. Thomas Frauenheim; Professor Dr. Thomas Niehaus
• Fachliche Zuordnung: Theoretische Physik der kondensierten Materie
• Förderung: Förderung von 2006 bis 2014
• Projektkennung: Deutsche Forschungsgemeinschaft (DFG) - Projektnummer 25002299

We aim to apply and validate existing State-of-the-Art density-functional-based approaches (Plane Wave, Local Orbital and minimal basis DFTB) in handshaking with quantum chemistry methods to perform calculations of molecules within break-junctions and on different metallic (Au, Cu) and semiconducting (Si) substrates in order to classify accurate and experimental relevant binding geometries. The central goal is to identify the lowest energy configurations and to improve the understanding on how different molecules react and bind to various substrates in vacuo and under environmental conditions. Molecular Dynamics simulations will be performed in order to study thermal fluctuations and dynamical properties of the adsorbates. This is particularly important in the context of break-junction and scanning probe experiments which in most cases show pronounced dynamical signatures due to repeated formation of conduction paths that can also be seen in noise signal. Having obtained the detailed atomic geometries, we will apply ab-initio calculations together with the DFTB code for characterising the electronic structure. Accurate quantum chemistry calculations with correlation-corrections will be applied to small systems to test and validate the effective single-particle approaches.Simulations of scanning tunnelling data (STM images and STS-spectra) will be performed within the framework of non-equilibrium Green¿s functions methods, in order to identify surface reconstructions and morphologies of different surfaces/adsorbates in comparison with experiments.We further will continue developing/improving our non-equilibrium Green¿s functions- DFTB techniques including many-body corrections to the electron-electron correlations and apply this for quantitative calculations of characteristic electronic transport signals across single molecules. This include I-V characteristics, IETS-data, noise analysis and power dissipation. In close collaboration with experimental investigations we aim to understand the molecule contact bonding configurations, the dynamical conformational behaviour of the molecules under applied bias and in coupling to the environment (contacts, dissipation, solution) and we aim to predict, how this will be reflected in the transport data and the functional behaviour of the molecular device.

• DFG-Verfahren: Schwerpunktprogramme
• Teilprojekt zu: SPP 1243: Quantum transport at the molecular scale