Nonequilibrium Green’s Functions

Balzer, Karsten; Bönitz, M.

doi:10.1007/978-3-642-35082-5_2

Cited by 11 publications

(11 citation statements)

References 55 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…[36][37][38] Here the accuracy of the results relies on the quality of the so called correlation self-energy Σ. If Σ = 0 then NEGF is equivalent to the (time-local) TD Hartree-Fock (HF) theory.…”

Section: Introductionmentioning

confidence: 99%

Charge Separation in Donor–C₆₀ Complexes with Real-Time Green Functions: The Importance of Nonlocal Correlations

et al. 2018

View full text Add to dashboard Cite

We use the Nonequilibrium Green's Function (NEGF) method to perform real-time simulations of the ultrafast electron dynamics of photoexcited donor-C60 complexes modeled by a Pariser-ParrPople Hamiltonian. The NEGF results are compared to mean-field Hartree-Fock (HF) calculations to disentangle the role of correlations. Initial benchmarking against numerically highly accurate time-dependent Density Matrix Renormalization Group calculations verifies the accuracy of NEGF. We then find that charge-transfer (CT) excitons partially decay into charge separated (CS) states if dynamical non-local correlation corrections are included. This CS process occurs in ∼ 10 fs after photoexcitation. In contrast, the probability of exciton recombination is almost 100% in HF simulations. These results are largely unaffected by nuclear vibrations; the latter become however essential whenever level misalignment hinders the CT process. The robust nature of our findings indicate that ultrafast CS driven by correlation-induced decoherence may occur in many organic nanoscale systems, but it will only be correctly predicted by theoretical treatments that include time-nonlocal correlations.

show abstract

Section: Introductionmentioning

confidence: 99%

Charge Separation in Donor–C₆₀ Complexes with Real-Time Green Functions: The Importance of Nonlocal Correlations

et al. 2018

View full text Add to dashboard Cite

show abstract

“…While previous LDA-DFT simulations describe the bulk bands reasonably well, they do not reproduce quantitatively the experimental energies of the end states (see further). To overcome these limitations, we apply a recently developed Green functions approach that gives access to spectral and magnetic properties of the system, see, for example, refs , , and . The electronic system is described with an effective Hubbard model, the Hamiltonian of which is expressed in terms of the operators ĉ i α † and ĉ j α that create and annihilate an electron with spin projection α at site i and j , respectively, where J = 2.7 eV is the hopping amplitude between adjacent lattice sites, and U is the on-site interaction.…”

mentioning

confidence: 99%

Correlated Topological States in Graphene Nanoribbon Heterostructures

2019

Self Cite

View full text Add to dashboard Cite

Finite graphene nanoribbon (GNR) heterostructures host intriguing topological in-gap states (Rizzo, D. J. et al. Nature 2018, 560, 204]). These states may be localized either at the bulk edges, or at the ends of the structure. Here we show that correlation effects (not included in previous density functional simulations) play a key role in these systems: they result in increased magnetic moments at the ribbon edges accompanied by a significant energy renormalization of the topological end states -even in the presence of a metallic substrate. Our computed results are in excellent agreement with the experiments. Furthermore, we discover a striking, novel mechanism that causes an energy splitting of the non-zero-energy topological end states for a weakly screened system. We predict that similar effects should be observable in other GNR heterostructures as well.

show abstract

“…Case (i) prepares the system in an ensemble with initial correlation, whereas in (ii) the non-interacting and thus known basis is used as reference. Adiabatic switching can then be employed to obtain a correlated state by turning on the interaction along the real time-axis 30 . Note that the chemical potential for the bosons is assumed to be zero as, in principle, an infinite number of them can be created.…”

Section: B Equations Of Motionmentioning

confidence: 99%

“…Since the general solution strategy in case of electron GFs is quite established [28][29][30] , we keep the discussion brief and rather focus on the modifications to be made for calculating the bosonic time-evolution.…”

Section: Numerical Implementationmentioning

confidence: 99%

“…On important application of the NEGF formalism is the prediction and interpretation of time-resolved angular-resolved photoemission spectra (tr-ARPES) 25 -a technique that is used in recent experiments on ultrafast dynamics of electronic 26 or phononic 27 band structures of correlated materials. The method relies on solving the equations of motion (EOM) for the Green's functions on the Keldysh timecontour [28][29][30] -the Kadanoff-Baym equations (KBEs) -with a proper choice of self-energy [31][32][33] , which in turn determines the form of collision integrals. This work is devoted to the extension of this formalism to coupled electronboson Hamiltonians (Sec.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Time-dependent many-body treatment of electron-boson dynamics: Application to plasmon-accompanied photoemission

2016

View full text Add to dashboard Cite

Recent experiments access the time-resolved photoelectron signal originating from plasmon satellites in correlated materials and address their build-up and decay in real time. Motivated by these developments, we present the Kadanoff-Baym formalism for the nonequilibrium time evolution of interacting fermions and bosons. In contrast to the fermionic case the bosons are described by second-order differential equations. Solution of the bosonic Kadanoff-Baym equations -which is the central ingredient of this work -requires substantial modification of the usual two-times electronic propagation scheme. The solution is quite general and can be applied to a number of problems, such as the interaction of electrons with quantized photons, phonons and other bosonic excitations. Here, the formalism is applied to the photoemission from a deep core hole accompanied by plasmon excitation. We compute the time-resolved photoelectron spectra and discuss the effects of intrinsic and extrinsic electron energy losses and their interference.

show abstract

Nonequilibrium Green’s Functions

Cited by 11 publications

References 55 publications

Charge Separation in Donor–C₆₀ Complexes with Real-Time Green Functions: The Importance of Nonlocal Correlations

Charge Separation in Donor–C₆₀ Complexes with Real-Time Green Functions: The Importance of Nonlocal Correlations

Correlated Topological States in Graphene Nanoribbon Heterostructures

Time-dependent many-body treatment of electron-boson dynamics: Application to plasmon-accompanied photoemission

Contact Info

Product

Resources

About

Nonequilibrium Green’s Functions

Cited by 11 publications

References 55 publications

Charge Separation in Donor–C60 Complexes with Real-Time Green Functions: The Importance of Nonlocal Correlations

Charge Separation in Donor–C60 Complexes with Real-Time Green Functions: The Importance of Nonlocal Correlations

Correlated Topological States in Graphene Nanoribbon Heterostructures

Time-dependent many-body treatment of electron-boson dynamics: Application to plasmon-accompanied photoemission

Contact Info

Product

Resources

About

Charge Separation in Donor–C₆₀ Complexes with Real-Time Green Functions: The Importance of Nonlocal Correlations

Charge Separation in Donor–C₆₀ Complexes with Real-Time Green Functions: The Importance of Nonlocal Correlations