Combined GW and dynamical mean-field theory: Dynamical screening effects in transition metal oxides

Tomczak, Jan M.; Casula, Michele; Miyake, Takashi; Aryasetiawan, Ferdi; Biermann, Silke

doi:10.1209/0295-5075/100/67001

Cited by 107 publications

(181 citation statements)

References 59 publications

(104 reference statements)

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“…In fact, the results obtained in the simplified "dual" approaches that include at least the electron-boson vertex γ are similar to those obtained by the GW +EDMFT method, which is conceptually and practically simpler than dual methods and has hence already been applied to realistic materials in a number of works [53][54][55][56].…”

Section: Beyond Gw+edmft: Comparison To Dual Bosons and Trilexsupporting

confidence: 61%

Influence of Fock exchange in combined many-body perturbation and dynamical mean field theory

et al. 2017

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In electronic systems with long-range Coulomb interaction, the nonlocal Fock-exchange term has a bandwidening effect. While this effect is included in combined many-body perturbation theory and dynamical mean field theory (DMFT) schemes, it is not taken into account in standard extended DMFT (EDMFT) calculations. Here, we include this instantaneous term in both approaches and investigate its effect on the phase diagram and dynamically screened interaction. We show that the largest deviations between previously presented EDMFT and GW +EDMFT results originate from the nonlocal Fock term, and that the quantitative differences are especially large in the strong-coupling limit. Furthermore, we show that the charge-ordering phase diagram obtained in GW +EDMFT methods for moderate interaction values is very similar to the one predicted by dual-boson methods that include the fermion-boson or four-point vertex. DOI: 10.1103/PhysRevB.95.245130 Dynamical mean field theory (DMFT) [1] self-consistently maps a correlated Hubbard lattice problem with local interactions onto an effective impurity problem consisting of a correlated orbital hybridized with a noninteracting fermionic bath. If the bath is integrated out, one obtains an impurity action with retarded hoppings. Extended dynamical mean field theory [2-10] (EDMFT) extends the DMFT idea to systems with long-range interactions. It does so by mapping a lattice problem with long-range interactions onto an effective impurity model with self-consistently determined fermionic and bosonic baths, or, in the action formulation, an impurity model with retarded hoppings and retarded interactions.While EDMFT captures dynamical screening effects and charge-order instabilities, it has been found to suffer from qualitative shortcomings in finite dimensions. For example, the charge susceptibility computed in EDMFT does not coincide with the derivative of the average charge with respect to a small applied field [11], nor does it obey local charge conservation rules [12] essential for an adequate description of collective modes such as plasmons.The EDMFT formalism has an even more basic deficiency: since it is based on a local approximation to the self-energy, it does not include even the first-order nonlocal interaction term, the Fock term. The combined GW +EDMFT [13][14][15] scheme corrects this by supplementing the local self-energy from EDMFT with the nonlocal part of the GW diagram, where G is the interacting Green's function and W the fully screened interaction. Indeed, the nonlocal Fock term [Gv] nonloc is included in the nonlocal [GW ] nonloc diagram. As described in more detail in Ref. [15] (see also the appendix of Ref.[16]), the GW +EDMFT method is formally obtained by constructing an energy functional of G and W , the Almbladh [17] functional , and by approximating as a sum of two terms, one containing all local diagrams (corresponding to EDMFT) and the other containing the simplest nonlocal correction (corresponding to the GW approximation [18]). This functional construct...

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Section: Beyond Gw+edmft: Comparison To Dual Bosons and Trilexsupporting

confidence: 61%

Influence of Fock exchange in combined many-body perturbation and dynamical mean field theory

et al. 2017

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“…Furthermore, we introduce a possibly smaller correlated orbital subspace C, whose effective local interactions are treated by means of an impurity construction within an extended DMFT approach similar to Refs. [15,16,18]. The fermionic and bosonic self-consistency loops are solved with bare propagators that incorporate the effect of screening channels outside I , while the self-consistently determined hybridization functions and retarded interactions of the impurity model also include retardation effects originating from nonlocal interactions and screening processes within I .…”

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confidence: 99%

When strong correlations become weak: Consistent merging of GW and DMFT

Boehnke¹,

Nilsson²,

et al. 2016

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The cubic perovskite SrVO 3 is generally considered to be a prototype strongly correlated metal with a characteristic three-peak structure of the d-electron spectral function, featuring a renormalized quasiparticle band in between pronounced Hubbard sidebands. Here we show that this interpretation, which has been supported by numerous "ab initio" simulations, has to be reconsidered. Using a fully self-consistent GW + extended dynamical mean-field theory calculation we find that the screening from nonlocal Coulomb interactions substantially reduces the effective local Coulomb repulsion, and at the same time leads to strong plasmonic effects. The resulting effective local interactions are too weak to produce pronounced Hubbard bands in the local spectral function, while prominent plasmon satellites appear at energies which agree with those of the experimentally observed sidebands. Our results demonstrate the important role of nonlocal interactions and dynamical screening in determining the effective interaction strength of correlated compounds. DOI: 10.1103/PhysRevB.94.201106 SrVO 3 has been considered a prototype strongly correlated metal ever since photoemission and inverse photoemission experiments 20 years ago [1] showed features at energies well outside the renormalized quasiparticle band. These satellites have been explained as Hubbard bands, because they appear in combined density functional + dynamical mean-field theory (LDA+DMFT) [2] simulations when the local Coulomb repulsion is chosen such that the experimentally observed mass renormalization is reproduced (see, e.g., Refs. [3][4][5]). Comparable values for the "Hubbard U " on the order of 5 eV were obtained by constrained local density approximation (LDA) [6,7] and used in DMFT calculations with static local interactions. The constrained random phase approximation (cRPA) [8] provides a systematic way of computing the dynamically screened interaction parameters consistent with the LDA band structure, and the resulting local U (ω) of the DMFT auxiliary system can be efficiently handled by state-of-the-art impurity solvers [9]. These more realistic calculations, however, produce a too strong renormalization of the quasiparticle band [10]. The missing ingredients in the LDA+DMFT + U (ω) approach are the nonlocal self-energy and polarization effects, and the additional screening of the U (ω) resulting from nonlocal Coulomb interactions within the low-energy subspace.A promising scheme, which can treat all these effects in a consistent manner, is the combination of the GW ab initio method [11] and extended DMFT (EDMFT) [12,13]. While this GW + EDMFT formalism has been tested on simple one-band Hubbard models [14][15][16][17], and several simplified versions have been applied to SrVO 3 [7,10,18,19], a fully self-consistent implementation in an ab initio setting has so far been hampered by the challenges of solving the bosonic selfconsistency loop for multiorbital systems and nontrivial issues related to a proper embedding of the EDMFT calculations into a ...

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“…Moreover, based on the charge susceptibility, we identify the electronic tendency of Si(111):Pb towards charge-ordering of the so-called 3 × 3 symmetry, which is indeed seen experimentally by scanning tunneling microscopy. Our work is the first one that addresses the electronic properties of real materials on the basis of fully self-consistent GW+DMFT calculations (for a non-selfconsistent calculation see [36], for self-consistent calculations for models see [37][38][39]). [48] The single-particle part of the Hamiltonian is calculated in the local density approximation of density functional theory.…”

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confidence: 99%

Long-Range Coulomb Interactions in Surface Systems: A First-Principles Description within Self-Consistently CombinedGWand Dynamical Mean-Field Theory

Hansmann

Ayral²,

Vaugier³

et al. 2013

Phys. Rev. Lett.

117

162

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Systems of adatoms on semiconductor surfaces display competing ground states and exotic spectral properties typical of two-dimensional correlated electron materials which are dominated by a complex interplay of spin and charge degrees of freedom. We report a fully ab initio derivation of low energy Hamiltonians for the adatom systems Si(111):X, with X=Sn, Si, C, Pb, that we solve within self-consistent combined GW and dynamical mean field theory ("GW+DMFT"). Calculated photoemission spectra are in agreement with available experimental data. We rationalize experimentally observed tendencies from Mott physics towards charge-ordering along the series as resulting from substantial long-range interactions.PACS numbers: 71.15. Mb, 73.20.At, 71.10.Fd, 71.30.h Understanding the electronic properties of materials with strong electronic Coulomb correlations remains one of the biggest challenges of modern condensed matter physics. The interplay of delocalization and interactions is not only at the origin of exotic ground states, but also determines the excitation spectra of correlated materials. The "standard model" of correlated fermions, the Hubbard model, in principle captures these phenomena. Yet, relating the model to the material on a microscopic footing remains a challenge. Even more importantly, the approximation of purely local Coulomb interactions can become severe in realistic materials, where long-range interactions and charge fluctuation physics cannot be neglected.Systems of adatoms on semiconducting surfaces, such as Si (111):X with X=Sn, C, Si, Pb, have been suggested [1] to be good candidates for observing low-dimensional correlated physics. Commonly considered to be realizations of the one-band Hubbard model and toy systems for investigating many-body physics on the triangular lattice, such surfaces have been explored experimentally [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18] and theoretically [19][20][21][22][23][24][25][26][27][28][29][30][31].These so-called α-phases show a remarkable variety of interesting physics including commensurate charge density wave (CDW) states [5,6,9] and isostructural metal to insulator transitions (MIT) [14]. However, while specific systems and/or phenomena have been investigated also theoretically, a comprehensive understanding including materials trends is still lacking. A central goal of our work is to present a unified picture that relates, within a single framework, different materials (adatom systems), placing them in a common phase diagram.We derive low-energy effective Hamiltonians ab initio from a combined density functional and constrained random phase approximation (cRPA) scheme [32] in the implementation of [33] (see also the extension to surface systems in [34]). While the first surprise are the relatively large values of the onsite interactions which we find to be of the order of the bandwidth (≈ 1 eV), most importantly we show that non-local interactions are large (nearestneighbor interaction of ≈ 0.5 eV) and, hence, an essential part of t...

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Combined GW and dynamical mean-field theory: Dynamical screening effects in transition metal oxides

Cited by 107 publications

References 59 publications

Influence of Fock exchange in combined many-body perturbation and dynamical mean field theory

Influence of Fock exchange in combined many-body perturbation and dynamical mean field theory

When strong correlations become weak: Consistent merging of GW and DMFT

Long-Range Coulomb Interactions in Surface Systems: A First-Principles Description within Self-Consistently CombinedGWand Dynamical Mean-Field Theory

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