Exchange-correlation functionals of i-DFT for asymmetrically coupled leads

Kurth, Stefan; Jacob, David

doi:10.1140/epjb/e2018-90184-7

Cited by 7 publications

(5 citation statements)

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“…For the couplings this has already been noted in Ref. 34. For the case of different temperatures in the leads, T α = T ± ∆T /2, it can be easily shown that this structure leads to the xc contribution to the many-body Seebeck coefficient (Eq.…”

Section: Single Impurity Anderson Modelsupporting

confidence: 60%

Steady-state density functional theory for thermoelectric effects

2019

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The recently proposed density functional theory for steady-state transport (i-DFT) is extended to include temperature gradients between the leads. Within this framework, a general and exact expression is derived for the linear Seebeck coefficient which can be written as the sum of the Kohn-Sham coefficient and an exchange-correlation contribution. The formalism is applied to the singleimpurity Anderson model for which approximate exchange-correlation functionals are suggested for temperatures both above and below the Kondo temperature. A certain structural property of the exchange-correlation potentials in the Coulomb blockade regime allows to recover an earlier result expressing the Seebeck coefficient in terms of quantities of equilibrium density functional theory. The numerical i-DFT results are compared to calculations with the numerical renormalization group over a wide range of temperatures finding a reasonable agreement while i-DFT comes at a much lower computational cost.

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Section: Single Impurity Anderson Modelsupporting

confidence: 60%

Steady-state density functional theory for thermoelectric effects

2019

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“…Notably, we found an example of a 'Markov-only' semigroup approximation that is non-perturbative in all parameters, yet simultaneously completely positive (CP) and trace-preserving (TP). It should be noted that this approximation relies only on the exact value of the stationary occupation n(∞) = 144,145 that are based on a mapping to the noninteracting limit studied here.…”

Section: Discussionmentioning

confidence: 99%

Five approaches to exact open-system dynamics: Complete positivity, divisibility, and time-dependent observables

Reimer

Wegewijs

Nestmann

et al. 2019

The Journal of Chemical Physics

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To extend the classical concept of Markovianity to an open quantum system, different notions of the divisibility of its dynamics have been introduced. Here we analyze this issue by five complementary approaches: equations of motion, real-time diagrammatics, Kraus-operator sums, as well as time-local (TCL) and nonlocal (Nakajima-Zwanzig) quantum master equations. As a case study featuring several types of divisible dynamics, we examine in detail an exactly solvable noninteracting fermionic resonant level coupled arbitrarily strongly to a fermionic bath at arbitrary temperature in the wideband limit. In particular, the impact of divisibility on the time-dependence of the observable level occupation is investigated and compared with typical Markovian approximations. We find that the loss of semigroup-divisibility is accompanied by a prominent reentrant behavior: Counter to intuition, the level occupation may temporarily increase significantly in order to reach a stationary state with smaller occupation, implying a reversal of the measurable transport current. In contrast, the loss of the so-called completely-positive divisibility is more subtly signaled by the prohibition of such current reversals in specific time-intervals. Experimentally, it can be detected in the family of transient currents obtained by varying the initial occupation. To quantify the nonzero footprint left by the system in its effective environment, we determine the exact time-dependent state of the latter as well as related information measures such as entropy, exchange entropy and coherent information.

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“…In order to construct such functionals, reliable reference results from other many-body methods are certainly very welcome [16,42,43]. However, once such approximations are available for a relatively simple system such as the Anderson model, generalizations to more complicated model systems (such as, e.g., multi-level systems) may actually be relatively straightforward [31,33,34,44]. Since multiterminal i-DFT is comparable in computational effort to standard LB-DFT calculations, it is therefore suitable to study systems currently inaccessible for accurate out-ofequilibrium many-body methods.…”

Section: Discussionmentioning

confidence: 99%

Nonequilibrium spectral functions from multiterminal steady-state density functional theory

et al. 2019

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Multi-terminal transport setups allow to realize more complex measurements and functionalities (e.g., transistors) of nanoscale systems than the simple two-terminal arrangement. Here the steady-state density functional formalism (i-DFT) for the description of transport through nanoscale junctions with an arbitrary number of leads is developed. In a three-terminal setup and in the ideal STM limit where one of the electrodes (the "STM tip") is effectively decoupled from the junction, the formalism allows to extract its non-equilibrium spectral function (at arbitrary temperature) while a bias is applied between the other two electrodes. Multi-terminal i-DFT is shown to be capable of describing the splitting of the Kondo resonance in an Anderson impurity in the presence of an applied bias voltage, as predicted by numerically exact many-body approaches. arXiv:1905.13070v1 [cond-mat.mes-hall]

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Exchange-correlation functionals of i-DFT for asymmetrically coupled leads

Cited by 7 publications

References 50 publications

Steady-state density functional theory for thermoelectric effects

Steady-state density functional theory for thermoelectric effects

Five approaches to exact open-system dynamics: Complete positivity, divisibility, and time-dependent observables

Nonequilibrium spectral functions from multiterminal steady-state density functional theory

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