Molecular Conductors with Center of Mass Motion

We study numerically the linear conductance of a molecular conductor that can oscillate between the source and drain electrodes.$^1$ This vibrational mode leads to an asymmetric modulation of the molecule-leads hopping parameters. By expanding this modulation up to the linear order, the conductance can be decomposed into two channels, the direct hopping and the phonon-assisted tunneling channels. The Kondo regime results show conductance dips that can be attributed to the destructive interference$^2$ of these two channels. If an internal vibrational mode is also active with the effect of symmetric modulation of the tunneling barriers, the particle-hole symmetry is broken and a Fano-like interference is observed. \newline \newline $^1$ K.A. Al-Hassanieh et al - Preprint \newline $^2$ B\"usser et al, cond-mat/0404426 (to appear in Phys. Rev B).