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

TY - JOUR

T1 - Generalization and applicability of the Landauer formula for nonequilibrium current in the presence of interactions

AU - Ness, H.

AU - Dash, L.K.

AU - Godby, R.

N1 - © 2010 American Physical Society. This is an author produced version of a paper published in Physical Review B. Uploaded in accordance with the publisher's self archiving policy.

PY - 2010/8/17

Y1 - 2010/8/17

N2 - Using nonequilibrium Green's functions (NEGFs), we calculate the current through an interacting region connected to noninteracting 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 nonequilibrium 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.

AB - Using nonequilibrium Green's functions (NEGFs), we calculate the current through an interacting region connected to noninteracting 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 nonequilibrium 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.

KW - CURRENT-VOLTAGE CHARACTERISTICS

KW - SCANNING-TUNNELING-MICROSCOPY

KW - KADANOFF-BAYM EQUATIONS

KW - GREENS-FUNCTIONS

KW - TRANSPORT-PROPERTIES

KW - MOLECULAR JUNCTIONS

KW - QUANTUM TRANSPORT

KW - ANDERSON IMPURITY

KW - CONDUCTANCE

KW - SCATTERING

UR - http://www.scopus.com/inward/record.url?scp=77957565497&partnerID=8YFLogxK

U2 - 10.1103/PhysRevB.82.085426

DO - 10.1103/PhysRevB.82.085426

M3 - Article

SN - 1098-0121

VL - 82

SP - -

JO - Physical Review B

JF - Physical Review B

IS - 8

M1 - 085426

ER -