Time-Resolved Electrochemical Spectroscopy of Charge Migration in Molecular Wires: Computational Evidence for Rich Electronic Dynamics

Abstract

Electrical conduction through a molecule tethered by thiol bridges between two gold clusters is examined from a time-dependent point of view. The shortest electronic time scale for charge migration is a few femtoseconds transit, which is too swift for coupling to the nuclei, that proceeds by super exchange. An order of magnitude slower transfer occurs sequentially through the lower-in-energy sigma bonds. The electronic structure computations are performed at a high level ab initio density functional theory level where the external electric fields are included as part of the Hamiltonian. The structure computed includes the thiol bridge as well as the gold trimer at either end of the molecule. The results shown in detail are for the saturated dithiohexane −S−(CH2)6−S− bridge between the two gold trimers.