136 research outputs found
Optimized effective potential method with exact exchange and static RPA correlation
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
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
We use a recently developed self-consistent 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 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}{\bf p}
parameterization in the context of these results.Comment: 9 pages, 1 figur
Quasiparticle self-consistent method; a basis for the independent-particle approximation
We have developed a new type of self-consistent scheme within the
approximation, which we call quasiparticle self-consistent (QS). We
have shown that QS rather well describes energy bands for a wide-range of
materials, including many where the local-density approximation fails. QS
contains physical effects found in other theories such as LDA, SIC and
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 QS, 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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