Propagation scheme for nonequilibrium dynamics of electron transport in nanoscale devices

Croy, Alexander; Saalmann, Ulf

doi:10.1103/physrevb.80.245311

Cited by 88 publications

(84 citation statements)

References 27 publications

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“…[9]. Thereby, the time evolution of the reduced single-electron density matrix ρ S;nm (t) = Tr S {ρ S (t)c † m c n } of the semiconductor is given by…”

Section: Methodsmentioning

confidence: 99%

“…We consider molecular structures, which, due to the influence of thermal fluctuations, exhibit rapidly oscillating electronic parameters, in particular on-site energies and intersite couplings. To incorporate these fluctuations correctly, we employ a time-dependent (TD) transport approach based on nonequilibrium Green's function (NEGF) theory [9,10]. This method was previously applied to study charge transport through DNA [6,7,11,12], and it has recently been extended to account for charge relaxation and electric field effects [8].…”

Section: Introductionmentioning

confidence: 99%

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Simulation of charge transport in organic semiconductors: A time-dependent multiscale method based on nonequilibrium Green's functions

Leitherer¹,

Jäger

Krause

et al. 2017

Phys. Rev. Materials

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In weakly interacting organic semiconductors, static disorder and dynamic disorder often have an important impact on transport properties. Describing charge transport in these systems requires an approach that correctly takes structural and electronic fluctuations into account. Here, we present a multiscale method based on a combination of molecular-dynamics simulations, electronic-structure calculations, and a transport theory that uses time-dependent nonequilibrium Green's functions. We apply the methodology to investigate charge transport in C 60 -containing self-assembled monolayers, which are used in organic field-effect transistors.

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“…[9]. Thereby, the time evolution of the reduced single-electron density matrix ρ S;nm (t) = Tr S {ρ S (t)c † m c n } of the semiconductor is given by…”

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Simulation of charge transport in organic semiconductors: A time-dependent multiscale method based on nonequilibrium Green's functions

Leitherer¹,

Jäger

Krause

et al. 2017

Phys. Rev. Materials

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“…Therefore, the squared-Lorentzian decomposition scheme of Eqs. (13) and (14) indeed preserves the positive semi-definiteness of reservoir spectral matrix, which guarantees the numerical stability and convergence of the resulting TDDFT-NEGF approach.…”

Section: B Application Of Psld Scheme Based Tddft-negf Approach To 2mentioning

confidence: 78%

“…5,6 Practical schemes of TDDFT for open systems (TDDFT-OS) have been proposed by various authors. 5,[7][8][9][10][11][12][13][14][15][16][17] TDDFT-OS methods have been applied to study timedependent electron transport through nanoelectronic devices, in which electron conductors of nanoscopic sizes are connected to macroscopic electrodes. Recently, by extending the applicability of TDDFT-OS, Wang et al have simulated the transient electron dynamics on two-dimensional (2D) surface of a graphene monolayer 18 and electron transfer across the interface of a molecule-graphene composite.…”

Section: Introductionmentioning

confidence: 99%

Time-dependent density functional theory for open systems with a positivity-preserving decomposition scheme for environment spectral functions

Wang

Zheng

Kwok

et al. 2015

The Journal of Chemical Physics

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Understanding electronic dynamics on material surfaces is fundamentally important for applications including nanoelectronics, inhomogeneous catalysis, and photovoltaics. Practical approaches based on time-dependent density functional theory for open systems have been developed to characterize the dissipative dynamics of electrons in bulk materials. The accuracy and reliability of such approaches depend critically on how the electronic structure and memory effects of surrounding material environment are accounted for. In this work, we develop a novel squared-Lorentzian decomposition scheme, which preserves the positive semi-definiteness of the environment spectral matrix. The resulting electronic dynamics is guaranteed to be both accurate and convergent even in the long-time limit. The long-time stability of electronic dynamics simulation is thus greatly improved within the current decomposition scheme. The validity and usefulness of our new approach are exemplified via two prototypical model systems: quasi-one-dimensional atomic chains and two-dimensional bilayer graphene.

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“…When the parameter values are η l = 1 and ζ l = π (2l − 1), this is referred to as the Matsubara expansion, but one can also improve the convergence of this series for finite N p by expressing the Fermi function as a finite continued fraction, and then poles of the Fermi function can be found as the solution to an eigenproblem for a tridiagonal matrix [106][107][108]. From the Matsubara expansion, one can write the lesser/greater self-energies as follows: …”

Section: Appendix D: Formulas For a Fast Numerical Implementationmentioning

confidence: 99%

Partition-free theory of time-dependent current correlations in nanojunctions in response to an arbitrary time-dependent bias

2017

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Working within the nonequilibrium Green's function formalism, a formula for the two-time current correlation function is derived for the case of transport through a nanojunction in response to an arbitrary time-dependent bias. The one-particle Hamiltonian and the wide-band limit approximation are assumed, enabling us to extract all necessary Green's functions and self-energies for the system, extending the analytic work presented previously [Ridley et al., Phys. Rev. B 91, 125433 (2015)]. We show that our expression for the two-time correlation function generalizes the Büttiker theory of shot and thermal noise on the current through a nanojunction to the time-dependent bias case including the transient regime following the switch-on. Transient terms in the correlation function arise from an initial state that does not assume (as is usually done) that the system is initially uncoupled, i.e., our approach is partition free. We show that when the bias loses its time dependence, the long-time limit of the current correlation function depends on the time difference only, as in this case an ideal steady state is reached. This enables derivation of known results for the single-frequency power spectrum and for the zero-frequency limit of this power spectrum. In addition, we present a technique which facilitates fast calculations of the transient quantum noise, valid for arbitrary temperature, time, and voltage scales. We apply this formalism to a molecular wire system for both dc and ac biases, and find a signature of the traversal time for electrons crossing the wire in the time-dependent cross-lead current correlations.

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Propagation scheme for nonequilibrium dynamics of electron transport in nanoscale devices

Cited by 88 publications

References 27 publications

Simulation of charge transport in organic semiconductors: A time-dependent multiscale method based on nonequilibrium Green's functions

Simulation of charge transport in organic semiconductors: A time-dependent multiscale method based on nonequilibrium Green's functions

Time-dependent density functional theory for open systems with a positivity-preserving decomposition scheme for environment spectral functions

Partition-free theory of time-dependent current correlations in nanojunctions in response to an arbitrary time-dependent bias

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