Applied-field effects on molecular switches

Using non-equilibrium Green's functions (NEGF), we calculate the current through an interacting region connected to non-interacting leads. The problem is reformulated in such a way that a Landauer-like term appears in the current as well as extra terms corresponding to non-equilibrium many-body effects. The interaction in the central region renormalizes not only the Green's functions but also the coupling at the contacts between the central region and the leads, allowing the total current to be further expressed as a generalized Landauer-like current formula. The general expression for the dynamical functional that renormalizes the contacts is provided. We analyze in detail under what circumstances Landauer-like approaches to the current, i.e. without contact renormalization, are valid for interacting electron-electron and/or electron-phonon systems. Numerical NEGF calculations are then performed for a model electron-phonon coupled system in order to validate our analytical approach. We show that the conductance for the off-resonant transport regime is adequately described by Landauer-like approach in the small-bias limit, while for the resonant regime the Landauer-like approach results depart from the exact results even at small finite bias. The validity of applying a Landauer-like approach to inelastic electron tunneling spectroscopy is also studied in detail.

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“…This model provides us with analytical expressions for the matrix elements of the leads' Green's functions at the terminal sites 50 :…”

Section: A Model Hamiltonian For Electron-phonon Couplingmentioning

confidence: 99%

Generalization and applicability of the Landauer formula for nonequilibrium current in the presence of interactions

2010

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“…In the following, we briefly review some contributions on the electron transport through a single organic molecule (or a few molecules) whose ends are connected to electron reservoirs. Calculations of the electronic transmission through such systems have been done for purely one-dimensional models [18][19][20][21][22][23][24][25] and two-dimensional models [26][27][28] . More realistic descriptions of the electrode/molecule system have also been developed.…”

Section: Introductionmentioning

confidence: 99%

Coherent electron-phonon coupling and polaronlike transport in molecular wires

2001

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We present a technique to calculate the transport properties through one-dimensional models of molecular wires. The calculations include inelastic electron scattering due to electron-lattice interaction. The coupling between the electron and the lattice is crucial to determine the transport properties in one-dimensional systems subject to Peierls transition since it drives the transition itself. The electron-phonon coupling is treated as a quantum coherent process, in the sense that no random dephasing due to electron-phonon interactions is introduced in the scattering wave functions. We show that charge carrier injection, even in the tunneling regime, induces lattice distortions localized around the tunneling electron. The transport in the molecular wire is due to polaron-like propagation. We show typical examples of the lattice distortions induced by charge injection into the wire. In the tunneling regime, the electron transmission is strongly enhanced in comparison with the case of elastic scattering through the undistorted molecular wire. We also show that although lattice fluctuations modify the electron transmission through the wire, the modifications are qualitatively different from those obtained by the quantum electron-phonon inelastic scattering technique. Our results should hold in principle for other one-dimensional atomic-scale wires subject to Peierls transitions. 85.30.Vw, 73.40.Gk, 73.61.Ph

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“…This problem has been of interest in recent years 11–21 and many authors use a Green's function approach, which essentially treats only the average current (or dc term) in the current. Here we illustrate how our time‐dependent model for a chain may be used and briefly discuss the relationship with the more usual approach.…”

Section: Model For Current Through Small Moleculesmentioning

confidence: 99%

“…The leads can also be modeled as long‐chain molecules. There are a number of treatments of currents in simple molecular systems to be found in the literature 12–19. Nearly all of these use Green functions and assume that there is an equilibrium so that the current is essentially constant.…”

Section: Introductionmentioning

confidence: 99%

Wavepacket propagation in simple molecular systems

Burrows

Amos

2001

Int J of Quantum Chemistry

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ABSTRACT:A combinatorial method for solving the time-dependent Schrödinger equation is used with the tight-binding approximation to consider the motion of wavepackets in chains and rings. A discussion of the relationship between the uncertainty principle and our results is given. We present calculations of charge densities, currents, and transmission coefficients, which illustrate the changes in the motion due to an impurity atom in the system and the effects of an imposed field with leads connected to the molecule.

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Applied-field effects on molecular switches

Cited by 11 publications

References 26 publications

Generalization and applicability of the Landauer formula for nonequilibrium current in the presence of interactions

Generalization and applicability of the Landauer formula for nonequilibrium current in the presence of interactions

Coherent electron-phonon coupling and polaronlike transport in molecular wires

Wavepacket propagation in simple molecular systems

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