Approach to Steady-State Transport in Nanoscale Conductors

Bushong, Neil; Sai, Na; Ventra, Massimiliano Di

doi:10.1021/nl0520157

Cited by 110 publications

(162 citation statements)

References 19 publications

(39 reference statements)

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“…Thus, the external perturbation is a local potential and the partitionfree approach can be combined with Time-Dependent Density Functional Theory 13,14,15,16 (TDDFT) to calculate total currents and densities in interacting systems. 7,8 The use of TDDFT in quantum transport is gaining ground 7,8,10,17,18,19,20,21,22,23,24,25,26,27,28,29 and several properties of the time-dependent exchangecorrelation potential and kernel have recently been discussed. 30,31,32,33,34 In a previous work 6 we have shown how a steady current develops under the influence of a constant bias.…”

Section: 910mentioning

confidence: 99%

Bound states inab initioapproaches to quantum transport: A time-dependent formulation

Stefanucci

2007

Phys. Rev. B

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In this work we study the role of bound electrons in quantum transport. The partition-free approach by Cini is combined with time-dependent density functional theory (TDDFT) to calculate total currents and densities in interacting systems. We show that the biased electrode-deviceelectrode system with bound states does not evolve towards a steady regime. The density oscillates with history-dependent amplitudes and, as a consequence, the effective potential of TDDFT oscillates too. Such time dependence might open new conductive channels, an effect which is not accounted for in any steady-state approach and might deserve further investigations.

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Section: 910mentioning

confidence: 99%

Bound states inab initioapproaches to quantum transport: A time-dependent formulation

Stefanucci

2007

Phys. Rev. B

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“…For example, in Figure 2 one would obtain a slightly different current if one fitted from 5 fs to 10 fs than if one fitted from 1 fs to 5 fs and neither result could be considered wrong. It has been shown recently 57,59,68 that, with existing computational resources, these numerical uncertainties can be minimized so that the currents obtained in this microcanonical picture agree essentially quantitatively with the true steady state currents. In particular, for the wire studied here we have verified that if the size of the leads is reduced by half the quasi-steady state current is unaffected.…”

Section: Conductance In a Model Junctionmentioning

confidence: 99%

“…[56][57][58]69 The details of our implementation are presented elsewhere. 59,60 Briefly, our algorithm integrates the time-dependent Kohn-Sham equations…”

Section: Real-time Density Functional Conductance Simulationsmentioning

confidence: 99%

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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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“…Equation (12) embodies the argument made by Lindblad 56 that a subdynamics exists only for an uncorrelated initial state, because, as a consequence of (6) and (12), it is possible to write…”

Section: B Equations With Memory Dressingmentioning

confidence: 99%

Decoherence due to contacts in ballistic nanostructures

Knežević

2008

Phys. Rev. B

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The active region of a ballistic nanostructure is an open quantum-mechanical system, whose nonunitary evolution (decoherence) towards a nonequilibrium steady state is determined by carrier injection from the contacts. The purpose of this paper is to provide a simple theoretical description of the contact-induced decoherence in ballistic nanostructures, which is established within the framework of the open systems theory. The active region's evolution in the presence of contacts is generally non-Markovian. However, if the contacts' energy relaxation due to electron-electron scattering is sufficiently fast, then the contacts can be considered memoryless on timescales coarsened over their energy relaxation time, and the evolution of the current-limiting active region can be considered Markovian. Therefore, we first derive a general Markovian map in the presence of a memoryless environment, by coarse-graining the exact short-time non-Markovian dynamics of an abstract open system over the environment memory-loss time, and we give the requirements for the validity of this map. We then introduce a model contact-active region interaction that describes carrier injection from the contacts for a generic two-terminal ballistic nanostructure. Starting from this model interaction and using the Markovian dynamics derived by coarse-graining over the effective memory-loss time of the contacts, we derive the formulas for the nonequilibrium steady-state distribution functions of the forward and backward propagating states in the nanostructure's active region. On the example of a double-barrier tunneling structure, the present approach yields an I-V curve that shows all the prominent resonant features. We address the relationship between the present approach and the Landauer-Büttiker formalism, and also briefly discuss the inclusion of scattering.

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Approach to Steady-State Transport in Nanoscale Conductors

Cited by 110 publications

References 19 publications

Bound states inab initioapproaches to quantum transport: A time-dependent formulation

Bound states inab initioapproaches to quantum transport: A time-dependent formulation

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

Decoherence due to contacts in ballistic nanostructures

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