Nonequilibrium transport with self-consistent renormalized contacts for a single-molecule nanodevice with electron-vibron interaction

Abstract

We present an application of a new formalism to treat the quantum transport properties of fully interacting nanoscale junctions [Phys. Rev. B 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 between the central region and the left electrode. We use a nonequilibrium 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 quasiresonant regime and for a wide range of parameters. They show that a nonequilibrium (i.e., bias dependent) static (i.e., energy independent) renormalization is obtained for the nominal hopping matrix element between the left electrode and the central region. Such a renormalization is highly nonlinear and nonmonotonic with the applied bias; however, it always leads to a reduction of the current and also affects the resonances in the conductance. Furthermore, we show that the relationship between the nonequilibrium charge susceptibility and dynamical conductance still holds even in the presence of crossing interaction.