Time-dependent partition-free approach in resonant tunneling systems

Stefanucci, Gianluca; Almbladh, Carl-Olof

doi:10.1103/physrevb.69.195318

Cited by 300 publications

(471 citation statements)

References 34 publications

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“…In TDDFT, the complicated problem of interacting electrons is mapped, in principle exactly, on the much simpler problem of noninteracting Kohn-Sham (KS) electrons moving in an effective local potential, thus providing a natural way to account for correlation effects in both leads and device region. 23,25 Since the method only involves the propagation of single-particle wave functions, it provides a computationally efficient way to study time-dependent phenomena in quantum transport. 26 The real-time TDDFT approach to transport will be described in Sec.…”

Section: Multistability In Time-dependent Density Functional Theorymentioning

confidence: 99%

“…23,49 The trace is taken over one-electron indices in the central region. Equation (19) includes initial many-body and embedding effects through the integral along the imaginary track of the contour (last term).…”

Section: Many-body Technique: Kadanoff-baym Equationsmentioning

confidence: 99%

“…[20][21][22][23][24][25][26][27][28][29][31][32][33][34] We first solve the steady-state equations of DFT and mean-field theory to determine the parameter range for bistability. Then we go beyond the current state-of-the-art and provide a TD description of the bistability phenomenon in adiabatic TDDFT [23][24][25][26][27][28][29] and TD mean-field theory. We show how to switch between different stable states by means of ultrafast gate voltages or external biases (driving fields).…”

Section: Introductionmentioning

confidence: 99%

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Correlation effects in bistability at the nanoscale: Steady state and beyond

et al. 2012

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The possibility of finding multistability in the density and current of an interacting nanoscale junction coupled to semi-infinite leads is studied at various levels of approximation. The system is driven out of equilibrium by an external bias and the nonequilibrium properties are determined by real-time propagation using both time-dependent density functional theory (TDDFT) and many-body perturbation theory (MBPT). In TDDFT the exchange-correlation effects are described within a recently proposed adiabatic local density approximation (ALDA). In MBPT the electron-electron interaction is incorporated in a many-body self-energy which is then approximated at the Hartree-Fock (HF), second-Born, and GW level. Assuming the existence of a steady state and solving directly the steady-state equations we find multiple solutions in the HF approximation and within the ALDA. In these cases we investigate whether and how these solutions can be reached through time evolution and how to reversibly switch between them. We further show that for the same cases the inclusion of dynamical correlation effects suppresses bistability.

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Section: Multistability In Time-dependent Density Functional Theorymentioning

confidence: 99%

Section: Many-body Technique: Kadanoff-baym Equationsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Correlation effects in bistability at the nanoscale: Steady state and beyond

et al. 2012

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“…The time-dependent version of density functional theory has also been used as framework for quantum transport. [23][24][25] This scheme is particularly useful for simulating transients and high frequency ac responses. Within the NEGF formalism, the many-body GW approxi-mation has been used to address correlated transport both under equilibrium 26 and nonequilibrium 27 conditions.…”

Section: Introductionmentioning

confidence: 99%

ConservingGWscheme for nonequilibrium quantum transport in molecular contacts

2008

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We give a detailed presentation of our recent scheme to include correlation effects in molecular transport calculations using the nonequilibrium Keldysh formalism. The scheme is general and can be used with any quasiparticle self-energy, but for practical reasons, we mainly specialize to the so-called GW self-energy, widely used to describe the quasiparticle band structures and spectroscopic properties of extended and lowdimensional systems. We restrict the GW self-energy to a finite, central region containing the molecule, and we describe the leads by density functional theory ͑DFT͒. A minimal basis of maximally localized Wannier functions is applied both in the central GW region and the leads. The importance of using a conserving, i.e., fully self-consistent, GW self-energy is demonstrated both analytically and numerically. We introduce an effective spin-dependent interaction which automatically reduces self-interaction errors to all orders in the interaction. The scheme is applied to the Anderson model in and out of equilibrium. In equilibrium at zero temperature, we find that GW describes the Kondo resonance fairly well for intermediate interaction strengths. Out of equilibrium, we demonstrate that the one-shot G 0 W 0 approximation can produce severe errors, in particular, at high bias. Finally, we consider a benzene molecule between featureless leads. It is found that the molecule's highest occupied molecular orbital-lowest unoccupied molecular orbital gap as calculated in GW is significantly reduced as the coupling to the leads is increased, reflecting the more efficient screening in the strongly coupled junction. For the I-V characteristics of the junction, we find that Hartree-Fock ͑HF͒ and G 0 W 0 ͓G HF ͔ yield results closer to GW than does DFT and G 0 W 0 ͓G DFT ͔. This is explained in terms of selfinteraction effects and lifetime reduction due to electron-electron interactions.

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“…After relaxation, say at time t 0 , we will bias the leads and study the screening dynamics from the transient to the steady state. This procedure simulates with high accuracy the so-called partition-free scheme, 22,23 as demonstrated in Refs. 24-26. We define the dot Green's function on the Keldysh contour as…”

Section: Kadanoff-baym Equations For the Interacting Resonant Levmentioning

confidence: 99%

Interacting resonant-level model with long-range interactions: Fast screening and suppression of the zero-bias conductance

2012

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The effects of long-range interactions in quantum transport are still largely unexplored, mainly due to the difficulty of devising efficient embedding schemes. In this work we present a substantial progress in the interacting resonant level model by reducing the problem to the solution of Kadanoff-Baym-like equations with a correlated embedding self-energy. The method allows us to deal with short-and long-range interactions and is applicable from the transient to the steady-state regime. Furthermore, memory effects are consistently incorporated and the results are not plagued by negative densities or nonconservation of the electric charge. We employ the method to calculate densities and currents with long-range interactions appropriate to low-dimensional leads, and show the occurrence of a jamming effect, which drastically reduces the screening time and suppresses the zero-bias conductance. None of these effects are captured by short-range model interactions.

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Time-dependent partition-free approach in resonant tunneling systems

Cited by 300 publications

References 34 publications

Correlation effects in bistability at the nanoscale: Steady state and beyond

Correlation effects in bistability at the nanoscale: Steady state and beyond

ConservingGWscheme for nonequilibrium quantum transport in molecular contacts

Interacting resonant-level model with long-range interactions: Fast screening and suppression of the zero-bias conductance

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