| 1. |
- Miyake, T., et al.
(författare)
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Effects of momentum-dependent self-energy in the electronic structure of correlated materials
- 2013
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Ingår i: Physical Review B (Condensed Matter and Materials Physics). - 1098-0121. ; 87:11
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Tidskriftsartikel (refereegranskat)abstract
- We study how the k dependence in the self-energy affects the quasiparticle band structure and one-particle spectral functions. It is known that, in electron-gas-like materials, the self-energy depends significantly on k and there is a strong cancellation between the k dependence and the energy dependence of the self-energy. Analysis of the GW self-energy reveals that, even in correlated materials with narrow bands, such as SrVO3, the self-energy significantly depends on k. When the nonlocal effect is neglected, the quasiparticle band structure is over-renormalized, yielding too large mass enhancement compared to the case of k-dependent self-energy. The present result suggests that partial cancellation between the frequency dependence and the k dependence in the self-energy is important when discussing the quasiparticle band structure of correlated materials. DOI: 10.1103/PhysRevB.87.115110
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| 2. |
- Sakuma, Rei, et al.
(författare)
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Ab initio study of the downfolded self-energy for correlated systems: Momentum dependence and effects of dynamical screening
- 2014
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Ingår i: Physical Review B (Condensed Matter and Materials Physics). - 1098-0121. ; 89:23
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Tidskriftsartikel (refereegranskat)abstract
- The electronic structure of strongly correlated systems is usually calculated by using an effective model Hamiltonian with a small number of states and an effective on-site interaction. The mode, however, neglects the frequency dependence of the interaction, which emerges as a result of dynamical screening processes not included in the model. The self-energy calculated in this kind of model within dynamical mean-field theory (DMFT) is usually assumed to contain on-site components only. To study the validity of model calculations for the simulation of realistic materials, we make a detailed comparison between the downfolded self-energy in a model Hamiltonian with static and dynamic on-site interaction and the full ab initio self-energy for Fe and SrVO3 within the GW approximation. We find that the model GW self-energy shows weaker k (momentum) dependence than the ab initio GW self-energy, which is attributed to the lack of the long-range interaction and of contributions from other electrons not included in the models. This weak k dependence is found to lead to an artificial narrowing of the quasiparticle band structure. Moreover, this band narrowing is stronger for the dynamic (frequency-dependent) interaction, due to a larger renormalization of the quasiparticle states. These findings indicate a crucial role of the k dependence of the self-energy and dynamical screening for the electronic structure of correlated systems. We also discuss the effects beyond the GW approximation for correlated systems by comparing the GW and DMFT results.
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| 3. |
- Sakuma, Rei, et al.
(författare)
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Self-energy and spectral function of Ce within the GW approximation
- 2012
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Ingår i: Physical Review B (Condensed Matter and Materials Physics). - 1098-0121. ; 86:24
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Tidskriftsartikel (refereegranskat)abstract
- To investigate how far the GW approximation can treat systems with strong on-site correlations, we perform calculations of the self-energies and spectral functions of alpha-and gamma-Ce within the GW approximation. For this strongly correlated material, the screened interaction exhibits a complex and rich structure which is attributed to strong particle-hole transitions involving localized 4f states. This structure in the screened interaction is carried over to the self-energy, which in turn yields spectral functions with multiple peaks. A satellite at around 5 eV above the Fermi level is formed, which is reminiscent of the experimentally observed upper Hubbard band, while the experimentally observed peak structure below the Fermi level at -2 eV and disappearance of the quasiparticle peak in the. phase are not reproduced. DOI: 10.1103/PhysRevB.86.245126
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