Received 24 Jun 2014, Accepted 16 Jul 2014
First published online 21 Jul 2014
The transport properties of single ferrocene molecules connected to nanoscopic gold electrodes are investigated in the framework of density functional theory (DFT) calculations using the non-equilibrium Green's function formalism. Our setup describes a molecular rotor, where one cyclopentadienyl (Cp) ring of the ferrocene molecule is fixed by the two electrodes, while the second ring is able to rotate. For small enough rotation energies the barrier between the eclipsed and staggered conformations of the ferrocene molecule ensures the functionality of a molecular oscillator. The changes in the transmission function introduced by the relative rotation angle between the two Cp rings are analyzed in both linear and non-linear bias regimes. For larger rotation energies, the device works in spinning mode. The real time behavior of the nanomechanical device is investigated using DFT-based molecular dynamics, which shows its feasibility for applications in terahertz regime. In the oscillating mode the natural frequencies are determined, while the spinning mode shows a remarkably reliable behavior with increasing rotation energy.