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Non-equilibrium transport with self-consistent renormalised contacts for a single-molecule nanodevice with electron-vibron interaction

We present an application of a new formalism to treat the quantum transport properties of fully interacting nanoscale junctions [Phys. Rev. B {\bf 84}, 235428 (2011)]. We consider a model single-molecule nanojunction in the presence of two kinds of electron-vibron interactions. In terms of electron density matrix, one interaction is diagonal in the central region and the second is off-diagonal in between the central region and the left electrode. We use a non-equilibrium Green's function technique to calculate the system's properties in a self-consistent manner. The interaction self-energies are calculated at the Hartree-Fock level in the central region and at the Hartree level for the crossing interaction. Our calculations are performed for different transport regimes ranging from the far off-resonance to the quasi-resonant regime, and for a wide range of parameters. They show that a non-equilibrium (i.e. bias dependent) static (i.e. energy independent) renormalisation is obtained for the nominal hopping matrix element between the left electrode and the central region. Such a renormalisation is highly non-linear and non-monotonic with the applied bias, however it always lead to a reduction of the current, and also affects the resonances in the conductance. Furthermore, we show that the relationship between the non-equilibrium charge susceptibility and dynamical conductance still holds even in the presence of crossing interaction.