Influence of the Core-Valence Interaction and of the Pseudopotential Approximation on the Electron Self-Energy in Semiconductors

Gómez-Abal, Ricardo I.; Li, Xin-Zheng; Scheffler, Matthias; Draxl, Claudia

doi:10.1103/physrevlett.101.106404

Cited by 114 publications

(107 citation statements)

References 27 publications

(27 reference statements)

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“…The discrepancy of ϳ0.2 eV is likely due to the core-valence exchange-correlation partitioning and pseudoization error of the pseudopotential GW approach. 78 In general our GW results are in good agreement with experiment, whereby the best agreement is achieved by GW 0 @ LDA+ U.…”

Section: -7supporting

confidence: 77%

“…44,77 GW calculations were performed using the FHI-gap ͑Green's function with augmented plane waves͒ package, a recently developed all-electron GW add on to WIEN2K. 29,[78][79][80] All important convergence parameters have been monitored to achieve an overall numerical accuracy of Ӎ0.05 eV. The Brillioun zone was sampled with 4 ϫ 4 ϫ 4 k meshes; unoccupied states with energy up to 136 eV were taken into account.…”

Section: E Computational Detailsmentioning

confidence: 99%

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First-principles modeling of localizeddstates with theGW@LDA+Uapproach

et al. 2010

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First-principles modeling of systems with localized d states is currently a great challenge in condensedmatter physics. Density-functional theory in the standard local-density approximation ͑LDA͒ proves to be problematic. This can be partly overcome by including local Hubbard U corrections ͑LDA+ U͒ but itinerant states are still treated on the LDA level. Many-body perturbation theory in the GW approach offers both a quasiparticle perspective ͑appropriate for itinerant states͒ and an exact treatment of exchange ͑appropriate for localized states͒, and is therefore promising for these systems. LDA+ U has previously been viewed as an approximate GW scheme. We present here a derivation that is simpler and more general, starting from the static Coulomb-hole and screened exchange approximation to the GW self-energy. Following our previous work for f-electron systems ͓H. Jiang, R. I. Gomez-Abal, P. Rinke, and M. Scheffler, Phys. Rev. Lett. 102, 126403 ͑2009͔͒ we conduct a systematic investigation of the GW method based on LDA+ U͑GW @LDA+U͒, as implemented in our recently developed all-electron GW code FHI-gap ͑Green's function with augmented plane waves͒ for a series of prototypical d-electron systems: ͑1͒ ScN with empty d states, ͑2͒ ZnS with semicore d states, and ͑3͒ late transition-metal oxides ͑MnO, FeO, CoO, and NiO͒ with partially occupied d states. We show that for ZnS and ScN, the GW band gaps only weakly depend on U but for the other transition-metal oxides the dependence on U is as strong as in LDA+ U. These different trends can be understood in terms of changes in the hybridization and screening. Our work demonstrates that GW @LDA+U with "physical" values of U provides a balanced and accurate description of both localized and itinerant states.

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Section: -7supporting

confidence: 77%

Section: E Computational Detailsmentioning

confidence: 99%

First-principles modeling of localizeddstates with theGW@LDA+Uapproach

et al. 2010

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“…The role of core-valence interactions has been discussed extensively in the context of quasiparticle gap calculations based on many-body perturbation theory within the GW approximation. [26][27][28][29][30][31][32][33] However, an inherent pp problem has not been noted in the context of KS gaps and well-constructed pps have been found to be highly accurate and transferable in a variety of applications. 22,23 While the FP-LAPW method is free of the pp approximation, it does employ its own approximations, e.g., the choice of basis sets, and these approximations may also be questioned.…”

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Examining the role of pseudopotentials in exact-exchange-based Kohn-Sham gaps

et al. 2009

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We present exact-exchange calculations of the Kohn-Sham gap, as well as the fundamental gap resulting from it, using highly accurate grid-based all-electron and pseudopotential approaches for prototypical diatomic molecules. Results obtained with pseudopotentials that have been constructed in a manner consistent with the exact-exchange functional agree with the all electron results for the cases studied. This confirms the reliability of the pseudopotential approximation for orbital-dependent functionals such as exact exchange

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“…38,42 Part of this controversy can be traced back to convergence difficulties in the early all-electron calculations, 43 while the influence of the pseudopotential approximation in GW turned out to be larger than initially anticipated. 44 To test the quality of the sc-GW spectra we chose the benzene molecule as a benchmark, for which the sc-GW spectral function in Fig. 3 is compared to the G 0 W 0 @HF and G 0 W 0 @PBE ones calculated using Eq.…”

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Unified description of ground and excited states of finite systems: The self-consistentGWapproach

et al. 2012

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GW calculations with a fully self-consistent Green's function G and screened interaction W -based on the iterative solution of the Dyson equation-provide a consistent framework for the description of groundand excited-state properties of interacting many-body systems. We show that for closed-shell systems selfconsistent GW reaches the same final Green's function regardless of the initial reference state. Self-consistency systematically improves ionization energies and total energies of closed-shell systems compared to G 0 W 0 based on Hartree-Fock and (semi)local density-functional theory. These improvements also translate to the electron density, as exemplified by an improved description of dipole moments, and permit us to assess the quality of ground-state properties such as bond lengths and vibrational frequencies. Many-body perturbation theory (MBPT) 1 in the GW approximation of the electronic self-energy 2,3 is presently the state-of-the-art method for describing the spectral properties of solids. 4,5 Recently, it has steadily gained popularity for molecules and nanosystems. 6 In addition, MBPT provides a prescription to extract total energies and structural properties from the GW approximation and therefore is a consistent theoretical framework for single-particle spectra and total energies.Due to its numerical cost and algorithmic difficulties, the GW method has only recently been applied self-consistently (i.e., nonperturbatively) to atoms, 7 molecules, 8 and molecular transport. 6 Predominantly, GW calculations are still performed perturbatively (one-shot G 0 W 0 ) on a set of singleparticle orbitals and eigenvalues obtained from a preceding density-functional theory 9 (DFT) or Hartree-Fock (HF) calculation. This procedure introduces a considerable starting-point dependence, 10-12 which can be eliminated by iterating the Dyson equation to self-consistency. [6][7][8]13 The resulting selfconsistent GW (sc-GW ) framework is a conserving approximation in the sense of Baym and Kadanoff 14 (i.e., it satisfies momentum, energy, and particle number conservation laws). sc-GW gives total energies 15 free from the ambiguities of the G 0 W 0 scheme, in which the results depend on the chosen total energy functional. 7 However, as in any self-consistent theory, the question remains if the self-consistent solution of the Dyson equation is unique. This issue is fundamentally different from the initial-state dependence of G 0 W 0 . For HF (Ref. 16) and local-density approximation (LDA)/generalized gradient approximation + U (GGA + U ) (Ref. 17) calculations, it is well known that the self-consistency cycle can reach many local minima instead of the global minimum. Moreover, a previous sc-GW study for the Be atom showed that normconserving pseudopotential calculations do not produce the same final GW Green's function (and the corresponding ionization potential) as all-electron calculations. 18 In this Rapid Communication, we demonstrate certain key aspects of the sc-GW approximation for closed-shell molecules that make...

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Influence of the Core-Valence Interaction and of the Pseudopotential Approximation on the Electron Self-Energy in Semiconductors

Cited by 114 publications

References 27 publications

First-principles modeling of localizeddstates with theGW@LDA+Uapproach

First-principles modeling of localizeddstates with theGW@LDA+Uapproach

Examining the role of pseudopotentials in exact-exchange-based Kohn-Sham gaps

Unified description of ground and excited states of finite systems: The self-consistentGWapproach

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