On simulation of local fluxes in molecular junctions

Cabra, Gabriel; Jensen, Annie Aarup; Galperin, Michael

doi:10.1063/1.5029252

Cited by 21 publications

(26 citation statements)

References 41 publications

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“…67 As implied in eqn (3) and (4), the current density through a molecular device is intimately linked to its electronic structure. 42,[78][79][80] As we examine the relation between structure and current density in cumulenes, we note that the s-band electrodes are depicted as dihydrogen molecules, and that we systematically utilize colour-schemes to show the direction of each vector as described by eqn (6) and (7) in the Methods section.…”

Section: Current Density Through Cumulenesmentioning

confidence: 99%

Helical orbitals and circular currents in linear carbon wires

et al. 2019

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Section: Current Density Through Cumulenesmentioning

confidence: 99%

Helical orbitals and circular currents in linear carbon wires

et al. 2019

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“…The molecular structures are coupled to semiinfinite contacts via sulfur atoms; each orbital of the latter is assumed to support Γ K = 0.1 eV electron exchange rate between the molecule and contact K (L or R) 48 . The contacts are modeled within the wide-band approximation 31 . While this level of molecule-contacts modeling is enough for illustration purposes, actual ab initio simulations should use a better basis set and perform realistic self-energy calculations.…”

Section: Numerical Resultsmentioning

confidence: 99%

“…We follow the work reported in Ref. 31 and consider a nanoscale system (a molecule) M coupled to two macroscopic contacts L and R, each at its own local equilibrium. Difference in electrochemical potentials on the two contacts causes electron flux through the molecule.…”

Section: Local Noise Spectroscopymentioning

confidence: 99%

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Local-noise spectroscopy for nonequilibrium systems

2018

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We introduce the notion, and develop the theory of local-noise spectroscopy (LNS)-a tool to study the properties of systems far from equilibrium by means of flux density correlations. As a test bed, we apply it to biased molecular junctions. This tool naturally extends those based on local fluxes, while providing complementary information on the system. As examples of the rich phenomenology that one can study with this approach, we show that LNS can be used to yield information on microscopic properties of bias-induced light emission in junctions, provide local resolution of intrasystem interactions, and employed as a nano-thermometry tool. Although LNS may, at the moment, be difficult to realize experimentally, it can nonetheless be used as a powerful theoretical tool to infer a wide range of physical properties on a variety of systems of present interest.

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“…1 Numerous approaches have been put forward to address vibrationally-coupled electron transport (VCET) processes in MJs, and similarly quantum dot systems. Partial list of approximate analytic methods include the inelastic scattering theory [56][57][58][59][60][61] , which only accounts for coherent scattering events, mixed quantum-classical approaches [62][63][64][65] where the vibrations are treated in a classical-like fashion, quantum master equation (QME) techniques [66][67][68][69][70][71][72][73][74][75][76][77] , which is often limited to weak moleculelead couplings and become inadequate to describe offresonant tunneling, and the nonequilibrium Green's function method (NEGF) [78][79][80][81][82][83][84][85][86][87][88] . Unambiguously, the NEGF is the state-of-the-art among these tools.…”

Section: Introductionmentioning

confidence: 99%

Generalized input-output method to quantum transport junctions. II. Applications

Liu

Segal

2020

Phys. Rev. B

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The interaction of electrons with atomic motion critically influences charge transport properties in molecular conducting junctions and quantum dot systems, and it is responsible for a plethora of transport phenomena. Nevertheless, theoretical tools are still limited to treat simple model junctions in specific parameter regimes. In this work, we put forward a generalized input-output method (GIOM) for studying charge transport in molecular junctions accounting for strong electron-vibration interactions and including electronic and phononic environments. The method radically expands the scope of the input-output theory, which was originally put forward to treat quantum optic problems. Based on the GIOM we derive a Langevin-type equation of motion for molecular operators, which posses a great generality and accuracy, and permits the derivation of a stationary charge current expression involving only two types of transfer rates. Furthermore, we devise the so-called "Polaron Transport in Electronic Resonance" (PoTER) approximation, which allows to feasibly simulate electron dynamics in generic tight-binding models with strong electron-vibration interactions. To illustrate the breadth of applications of the GIOM-PoTER technique, we analyze prototype molecular junction models with primary and secondary vibrational modes. For short chains, the charge current reduces to known limits and reasonably agrees with exact numerical simulations (when available). For extended junctions the current displays a turnover from phonon-assisted to phonon-suppressed transport. Nevertheless, the onset of ohmic behavior requires extensions beyond the PoTER approximation. As an additional application, we consider a cavity-coupled molecule junction. Here we identify a cavity-induced suppression of charge current in the single-site case, and observe signatures of polariton formation in the current-voltage characteristics in the strong light-matter coupling regime. A critical understanding gained from the GIOM-PoTER scheme is that the single-site vibrationally-coupled model is deceptively simpler, and amenable to approximations than multi-site models. Therefore, benchmarking of methods should not be concluded with the single-site case. The work manifests that the input-output framework, which is normally employed in quantum optics, can serve as a powerful and feasible tool in the realm of electron transport junctions.

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On simulation of local fluxes in molecular junctions

Cited by 21 publications

References 41 publications

Helical orbitals and circular currents in linear carbon wires

Helical orbitals and circular currents in linear carbon wires

Local-noise spectroscopy for nonequilibrium systems

Generalized input-output method to quantum transport junctions. II. Applications

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