Successes and Failures of Kadanoff-Baym Dynamics in Hubbard Nanoclusters

Friesen, M. Puig von; Verdozzi, Claudio; Almbladh, Carl-Olof

doi:10.1103/physrevlett.103.176404

Cited by 116 publications

(186 citation statements)

References 28 publications

(40 reference statements)

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“…(17) requires a transformation into equations for real times, known as KB equations, which are then solved by time propagation. 16,20,21,52 From the knowledge of the Green's function any one-particle property of the system can be extracted. In particular, the time-dependent density can be obtained from the lesser Green's function as…”

Section: Many-body Technique: Kadanoff-baym Equationsmentioning

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: Many-body Technique: Kadanoff-baym Equationsmentioning

confidence: 99%

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

et al. 2012

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“…With the entry of nanoscience the use of GW has been extended to low-dimensional systems and nanostructures [21][22][23][24][25][26][27][28][29][30][31] and more recently even nonequilibrium phenomena such as quantum transport. [32][33][34][35][36] In view of this trend it is important to establish the performance of the GW approximation for other systems than the crystalline solids. In this work we present first-principles benchmark GW calculations for a series of small molecules.…”

Section: Introductionmentioning

confidence: 99%

Fully self-consistent GW calculations for molecules

2010

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We calculate single-particle excitation energies for a series of 34 molecules using fully self-consistent GW, one-shot G 0 W 0 , Hartree-Fock ͑HF͒, and hybrid density-functional theory ͑DFT͒. All calculations are performed within the projector-augmented wave method using a basis set of Wannier functions augmented by numerical atomic orbitals. The GW self-energy is calculated on the real frequency axis including its full frequency dependence and off-diagonal matrix elements. The mean absolute error of the ionization potential ͑IP͒ with respect to experiment is found to be 4.4, 2.6, 0.8, 0.4, and 0.5 eV for DFT-PBE, DFT-PBE0, HF, G 0 W 0 ͓HF͔, and self-consistent GW, respectively. This shows that although electronic screening is weak in molecular systems, its inclusion at the GW level reduces the error in the IP by up to 50% relative to unscreened HF. In general GW overscreens the HF energies leading to underestimation of the IPs. The best IPs are obtained from one-shot G 0 W 0 calculations based on HF since this reduces the overscreening. Finally, we find that the inclusion of core-valence exchange is important and can affect the excitation energies by as much as 1 eV.

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“…The NEG technique is used in a wide variety of fields, treating both real and model systems [102][103][104][105][106][107][108][109][110][111]. The method has the advantage of having a direct connection to MBPT, in which conserving [40] approximations of increasing complexity can be constructed systematically and where memory effects [100,101] are automatically built in.…”

Section: Kadanoff-baym Dynamicsmentioning

confidence: 99%

“…In the ground state, before the perturbation has been introduced, the systems are in the low density regime. The reason of this choice is that of the three MBA:s we consider, one of them, the TMA, performs rather well at these densities [111], while the BA and GWA are not good in any of the regimes we considered.…”

Section: A Inversion Of the Non-interacting Responsementioning

confidence: 99%

Some open questions in TDDFT: Clues from lattice models and Kadanoff–Baym dynamics

et al. 2011

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Two aspects of TDDFT, the linear response approach and the adiabatic local density approximation, are examined from the perspective of lattice models. To this end, we review the DFT formulations on the lattice and give a concise presentation of the time-dependent Kadanoff-Baym equations, used to asses the limitations of the adiabatic approximation in TDDFT. We present results for the density response function of the 3D homogeneous Hubbard model, and point out a drawback of the linear response scheme based on the linearized Sham-Schlüter equation. We then suggest a prescription on how to amend it. Finally, we analyze the time evolution of the density in a small cubic cluster, and compare exact, adiabatic-TDDFT and Kadanoff-Baym-Equations densities. Our results show that non-perturbative (in the interaction) adiabatic potentials can perform quite well for slow perturbations but that, for faster external fields, memory effects, as already present in simple many-body approximations, are clearly required.

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Successes and Failures of Kadanoff-Baym Dynamics in Hubbard Nanoclusters

Cited by 116 publications

References 28 publications

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

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

Fully self-consistent GW calculations for molecules

Some open questions in TDDFT: Clues from lattice models and Kadanoff–Baym dynamics

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