BETA - bremen initiative on eletronic transport in advanced materials: Atomistic approaches towards quantum transport dynamics across single molecules: break junctions and surface adsorbed geometries

Prof. Dr. habil. Thomas Frauenheim, Universität Bremen [Homepage]

Dr. Thomas Niehaus, Universität Bremen [Homepage]

We aim to apply and validate existing State-of-the-Art density-functional-based ap-proaches (Plane Wave, Local Orbital and minimal basis DFTB) in handshaking with quantum chemistry methods to perform calculations of molecules in break-junction and STM experiments.
Simulations of scanning tunnelling data (STM images and STS-spectra) will be per-formed 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. Collaboration with experimental groups working on this topic (Prof. Pascual and Prof. Tautz) are already established.
Moreover, the non-equilibrium Green’s function formalism will allow to describe in detail the I-V characteristics of such systems with particular interest in the inelastic effects in-duced by electron-phonon interactions. This can lead to the evaluation of the inelastic component of the current and so to the power dissipation in the molecule. The knowl-edge of the power dissipated can be used to evaluate the heating of the molecule and its stability on the substrate and between the contacts.
While with respect to the electron-phonon interaction the focus is more on the applica-tion of already existing and well tested methodology, we will also continue work on method development in the field of electron-electron interactions. Here two different routes will be followed, namely time-dependent density functional theory and many-body perturbation theory in the GW approximation. The conjunctive goal is an improved quan-titative description of charge transfer across single molecules.