Finite-temperature Mott transitions in the multiorbital Hubbard model

Koga, Akihisa; Suga, Sei–ichiro; Kawakami, Norio

doi:10.1103/physrevb.72.085112

Cited by 55 publications

(77 citation statements)

References 63 publications

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“…This yields the reference system d) which is a set of disconnected single-impurity Anderson models with n s < ∞ sites each. Qualitatively, the results of the two-site dynamicalimpurity approximation 27,63,64,65,66 (Fig. 3c) are already close to the n s = ∞ limit.…”

Section: Dynamical Mean-field Theorymentioning

confidence: 72%

“…3c,d). Note that the disorder part is still the same as in the original model (65), as it is required to justify Eq. (60).…”

Section: Mean-field Approximationsmentioning

confidence: 99%

“…The site index x can be suppressed in this case. This reflects the translational symmetry of averaged quantities in the original model (65). Due to the decoupling of the original sites, the reference system yields a trial self-energy which is local.…”

Section: Mean-field Approximationsmentioning

confidence: 99%

“…81 To be definite, we again consider the Anderson model Eq. (65). The reference system generating the M-CPA is shown in Fig.…”

Section: A Variational Cluster Approachmentioning

confidence: 99%

“…For the case of the pure Hubbard model without disorder is has proven to be very instructive and successful. 27,63,64,65,66 It provides a handy mean-field approach which is able to reproduce qualitatively the DMFT phase diagram for the Mott transition in the single-band model and which has been employed to study more complex two-and multi-orbital systems. A recent application 67 to the Anderson-Hubbard model has shown that the approach can straightforwardly be extended to disordered (and interacting) systems along the lines described here.…”

Section: B Two-site Approximationmentioning

confidence: 99%

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Self-energy-functional theory for systems of interacting electrons with disorder

Potthoff

Balzer

2007

Phys. Rev. B

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Based on a functional-integral formalism, a generalization of the self-energy-functional theory (SFT) is proposed which is applicable to systems of interacting electrons with disorder. Similar to the pure case without disorder, a variational principle is set up which gives the physical (disorder) self-energy as a stationary point of the (averaged) grand potential. Although the resulting self-energy functional turns out to be more complicated, the formal structure of the theory can be retained since the unknown part of the functional is universal. This allows to construct nonperturbative and thermodynamically consistent approximations via searching for a stationary point on a restricted domain of the functional. The theory and the possible approximations are worked out for models with local interactions and local disorder. This results in a derivation of different mean-field approaches and various cluster extensions, including well-known concepts as the statistical dynamical mean-field theory, the molecular coherent-potential approximation and the dynamical cluster approximation. Due to the common formal framework provided by the SFT, one achieves a general systematization of dynamical approaches, i.e. approaches based on the spectrum of oneparticle excitations. New mean-field and new cluster schemes naturally appear in this framework and complement the existing ones. Their prospects for future applications are discussed.

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Section: Dynamical Mean-field Theorymentioning

confidence: 72%

“…3c,d). Note that the disorder part is still the same as in the original model (65), as it is required to justify Eq. (60).…”

Section: Mean-field Approximationsmentioning

confidence: 99%

Section: Mean-field Approximationsmentioning

confidence: 99%

“…81 To be definite, we again consider the Anderson model Eq. (65). The reference system generating the M-CPA is shown in Fig.…”

Section: A Variational Cluster Approachmentioning

confidence: 99%

Section: B Two-site Approximationmentioning

confidence: 99%

See 3 more Smart Citations

Self-energy-functional theory for systems of interacting electrons with disorder

Potthoff

Balzer

2007

Phys. Rev. B

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Nonempirical Calculation of Superconducting Transition Temperatures in Light‐Element Superconductors

et al. 2017

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Recent progress in the fully nonempirical calculation of the superconducting transition temperature (T ) is reviewed. Especially, this study focuses on three representative light-element high-T superconductors, i.e., elemental Li, sulfur hydrides, and alkali-doped fullerides. Here, it is discussed how crucial it is to develop the beyond Migdal-Eliashberg (ME) methods. For Li, a scheme of superconducting density functional theory for the plasmon mechanism is formulated and it is found that T is dramatically enhanced by considering the frequency dependence of the screened Coulomb interaction. For sulfur hydrides, it is essential to go beyond not only the static approximation for the screened Coulomb interaction, but also the constant density-of-states approximation for electrons, the harmonic approximation for phonons, and the Migdal approximation for the electron-phonon vertex, all of which have been employed in the standard ME calculation. It is also shown that the feedback effect in the self-consistent calculation of the self-energy and the zero point motion considerably affect the calculation of T . For alkali-doped fullerides, the interplay between electron-phonon coupling and electron correlations becomes more nontrivial. It has been demonstrated that the combination of density functional theory and dynamical mean field theory with the ab initio downfolding scheme for electron-phonon coupled systems works successfully. This study not only reproduces the experimental phase diagram but also obtains a unified view of the high-T superconductivity and the Mott-Hubbard transition in the fullerides. The results for these high-T superconductors will provide a firm ground for future materials design of new superconductors.

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Magnetic transitions in strong coupling expansions for nearly degenerate states

2012

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A strong coupling expansion for a two-band Hubbard model on two sites with nearly degenerate states is considered. A comparative analysis is performed for different schemes of perturbation theory which are applicable to systems with nearly degenerate states. A fourth order approach which builds on a four-dimensional low-energy subspace with nearly degenerate states captures accurately the transition from an antiferromagnetic to a ferromagnetic ground state at large on-site Coulomb interaction.

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Finite-temperature Mott transitions in the multiorbital Hubbard model

Cited by 55 publications

References 63 publications

Self-energy-functional theory for systems of interacting electrons with disorder

Self-energy-functional theory for systems of interacting electrons with disorder

Nonempirical Calculation of Superconducting Transition Temperatures in Light‐Element Superconductors

Magnetic transitions in strong coupling expansions for nearly degenerate states

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