136 research outputs found

    Optimized effective potential method with exact exchange and static RPA correlation

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    We present a new density-functional method of the self-consistent electronic-structure calculation which does not exploit any local density approximations (LDA). We use the exchange-correlation energy which consists of the exact exchange and the correlation energies in the random-phase approximation. The functional derivative of the correlation energy with respect to the density is obtained within a static approximation. For transition metals, it is shown that the correlation potential gives rise to a large contribution which has the opposite sign to the exchange potential. Resulting eigenvalue dispersions and the magnetic moments are very close to those of LDA's and the experiments.Comment: 12pages. 4 figure

    Model-mapped random phase approximation to evaluate superconductivity in the fluctuation exchange approximation from first principles

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    We have applied the model-mapped RPA [H. Sakakibara et al., J. Phys. Soc. Jpn. 86, 044714 (2017)] to the cuprate superconductors La2CuO4 and HgBa2CuO4, resulting two-orbital Hubbard models. All the model parameters are determined based on first-principles calculations. For the model Hamiltonians, we perform fluctuation exchange calculation. Results explain relative height of Tc observed in experiment for La2CuO4 and HgBa2CuO4. In addition, we give some analyses for the interaction terms in the model, especially comparisons with those of the constrained RPA.Comment: 7 pages, 4 figure

    Ab-initio Prediction of Conduction Band Spin Splitting in Zincblende Semiconductors

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    We use a recently developed self-consistent GWGW approximation to present systematic \emph{ab initio} calculations of the conduction band spin splitting in III-V and II-V zincblende semiconductors. The spin orbit interaction is taken into account as a perturbation to the scalar relativistic hamiltonian. These are the first calculations of conduction band spin splittings based on a quasiparticle approach; and because the self-consistent GWGW scheme accurately reproduces the relevant band parameters, it is expected to be a reliable predictor of spin splittings. The results are compared to the few available experimental data and a previous calculation based on a model one-particle potential. We also briefly address the widely used {\bf k}\cdot{\bf p} parameterization in the context of these results.Comment: 9 pages, 1 figur

    Quasiparticle self-consistent GWGW method; a basis for the independent-particle approximation

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    We have developed a new type of self-consistent scheme within the GWGW approximation, which we call quasiparticle self-consistent GWGW (QSGWGW). We have shown that QSGWGW rather well describes energy bands for a wide-range of materials, including many where the local-density approximation fails. QSGWGW contains physical effects found in other theories such as LDA+U+U, SIC and GWGW in a satisfactory manner without many of their drawbacks (partitioning of itinerant and localized electrons, adjustable parameters, ambiguities in double-counting, etc.). We present some theoretical discussion concerning the formulation of QSGWGW, including a prescriptino for calculating the total energy. We also address several key methodological points needed for implementation. We then show convergence checks and some representative results in a variety of materials.Comment: v2:the same as previous version --but better tex file; v3:add appendix and modify introduction,mainly; v4 mainly, theoretical section (IB IC) are renewe
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