Electron-Vibration Coupling: Toward Enhanced Charge Transfer at the Nanoscale

Justin E. Elenewski
George Washington University, Washington DC

Electron-phonon coupling is responsible for manifold condensed matter phenomena, ranging from resistive scattering to the emergence of the conventional superconductivity. This process becomes particularly nuanced at the nanoscale, where finite size effects and local heating can have a marked impact on device characteristics. While generally deleterious, recent experiments have demonstrated that certain electronic excitations may be optically controlled through their coupling to individual vibrational modes.

I will present an explicit theoretical treatment of this process, in which contemporary electronic structure methods (DFT/TDDFT) are conjoined with functional mode analysis and an analytical model for vibrationally-coupled electron transfer. This approach is used to address three examples in which vibrational coupling can act to promote charge migration, including excited electron injection at the molecule/semiconductor interface, exciton formation in molecular solids, and photo induced electron transfer between DNA and a `tag' for biomolecular imaging. In each case the promoting ensemble contains only a few vibrational modes, all outpacing scattering even in a strong thermal background. This suggests that external control may be applied to engineer the dynamics of these systems for energy harvesting or metrological applications. I will conclude with a brief discussion of new methods to treat coherent transport in open quantum systems, with an eye toward the explicit inclusion of similar, finite-temperature dynamics.