Time-dependent quantum transport: An exact formulation based on TDDFT

Stefanucci, Gianluca; Almbladh, Carl-Olof

doi:10.1209/epl/i2004-10043-7

Cited by 133 publications

(191 citation statements)

References 21 publications

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“…[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%

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: Introductionmentioning

confidence: 99%

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

et al. 2012

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“…[2][3][4][5][6][7][8][9][10] As a formally rigorous and numerically tractable approach, TDDFT promises real-time simulations on ultrafast electron transport through realistic electronic devices or structures. In early attempts, finite source-device-drain systems were treated by the conventional TDDFT for isolated systems.…”

Section: Introductionmentioning

confidence: 99%

“…By employing the NEGF approach and a partition-free scheme, Stefanucci and Almbladh have derived the exact equations of motion for the two-time Green's functions within TDDFT framework. 2 They and their coworkers have further proposed a practical scheme in which the electronic wavefunction propagates in time domain subject to open boundaries. 3 The resulting numerical method has been tested on model systems.…”

Section: Introductionmentioning

confidence: 99%

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Time-dependent density functional theory for quantum transport

2013

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Based on our earlier works [Phys. Rev. B 75, 195127 (2007) & J. Chem. Phys. 128, 234703 (2008], we propose a formally exact and numerically convenient approach to simulate time-dependent quantum transport from first-principles. The proposed approach combines time-dependent density functional theory with quantum dissipation theory, and results in a useful tool for studying transient dynamics of electronic systems. Within the proposed exact theoretical framework, we construct a number of practical schemes for simulating realistic systems such as nanoscopic electronic devices. Computational cost of each scheme is analyzed, with the expected level of accuracy discussed. As a demonstration, a simulation based on the adiabatic wide-band limit approximation scheme is carried out to characterize the transient current response of a carbon nanotube based electronic device under time-dependent external voltages.

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“…Recently, an alternative microcanonical prescription for describing electron transport has been proposed 52,53 . Here, the entire junction (molecule+leads) begins in equilibrium and one monitors the real-time response of the junction to a time-dependent applied bias.…”

Section: Introductionmentioning

confidence: 99%

Exchange and correlation in molecular wire conductance: Nonlocality is the key

Evans

Vydrov

Voorhis

2009

The Journal of Chemical Physics

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We study real-time electron dynamics in a molecular junction with a variety of approximations to the electronic structure, toward the ultimate aim of determining what ingredients are crucial for the accurate prediction of charge transport. We begin with real-time, all-electron simulations using some common density functionals that differ in how they treat long-range Hartree-Fock exchange. We find that the inclusion or exclusion of non-local exchange is the dominant factor determining the transport behavior, with all semilocal contributions having a smaller effect. In order to study non-local correlation, we first map our junction onto a simple Pariser-Parr-Pople (PPP) model Hamiltonian. The PPP dynamics are shown to faithfully reproduce the all-electron results, and we demonstrate that non-local correlation can be readily included in the model space using the generator coordinate method (GCM). Our PPP-GCM simulations suggest that non-local correlation has a significant impact on the I-V character that is not captured even qualitatively by any of the common semilocal approximations to exchange and correlation. The implications of our results for transport calculations are discussed.

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Time-dependent quantum transport: An exact formulation based on TDDFT

Cited by 133 publications

References 21 publications

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

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

Time-dependent density functional theory for quantum transport

Exchange and correlation in molecular wire conductance: Nonlocality is the key

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