We study the linear-response and out-of-equilibrium transport properties of nanoscale junctions using a coherent Landauer-Buttiker framework in synchrony with density-functional theory and many-body perturbation theory. The Landauer-Buttiker method is a standard framework for describing the coherent propagation of electronic waves across devices based on the calculated scattering states.
We compute transport and optical properties using many-body perturbation theory within the GW approximation and the Bethe-Salpeter Equation for systems where standard-DFT approaches fail, like organic molecules and their crystals. For such systems, standard approximations to DFT exchange-correlation energy are not sufficient because of self-interaction and derivative discontinuity errors, and the lack of non-locality in the approximate exchange-correlation functional.
We work to develop, understand the limitations of, and apply new functionals, such as range-separated hybrids and van der Waals density functionals, for treating spectroscopy and weak, non-covalent interactions in condensed-phase systems. Applications include organic donor-acceptor interfaces relevant to solar cells, CO2 capture in metal-organic frameworks, and molecular adsorbates on metal surfaces. More »