Coulomb interaction parameters in bcc iron: an LDA+DMFT study

Белозеров, А. С.; Анисимов, В. И.

doi:10.1088/0953-8984/26/37/375601

Cited by 32 publications

(44 citation statements)

References 86 publications

(105 reference statements)

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“…A number of earlier DFT+DMFT works [25][26][27] chose the parameter U of about 2 eV. More recent direct calculations within the constrained local-density and random-phase (cRPA) approximations [28,29] predict the static value of the Slater parameter F U 0 = in the range between 3 and 4 eV, only about 10% of reduction of the ambientcondition value was obtained in cRPA calculations for the inner-core atomic volume [15]. The 30% increase of the value used in DFT+DMFT calculations with respect to the static cRPA value was suggested in [30] to effectively account for the frequency dependence of the Coulomb vertex.…”

Section: Methodsmentioning

confidence: 99%

Electron–electron scattering and thermal conductivity ofϵ-iron at Earth’s core conditions

Pourovskii¹,

Mravlje²,

Georges³

et al. 2017

New J. Phys.

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The electronic state and transport properties of hot dense iron are of the utmost importance for the understanding of Earth's interior. Combining state-of-the-art density functional and dynamical mean field theories we study the impact of electron correlations on the electrical and thermal resistivity of hexagonal close-packed ò-Fe at Earth's core conditions and show that the electron-electron scattering in ò-Fe exhibit a nearly perfect Fermi-liquid (FL) behavior. Accordingly, the quadratic dependence of the scattering rate, typical of FLs, leads to a modification of the Wiedemann-Franz law and suppresses the thermal conductivity with respect to the electrical one. The consequence is a significant increase of the electron-electron thermal resistivity, which is found to be of comparable magnitude to the electron-phonon one.

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Section: Methodsmentioning

confidence: 99%

Electron–electron scattering and thermal conductivity ofϵ-iron at Earth’s core conditions

Pourovskii¹,

Mravlje²,

Georges³

et al. 2017

New J. Phys.

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“…Many-electron effects in iron are expected to arise due to the on-site Coulomb repulsion between rather localized 3d states hybridized with itinerant 4s bands. The typical width W of the iron 3d band is in the range of 5 to 6 eV for the ambient pressure; the estimated value of the local Coulomb interaction parameter U (Slater F 0 ) is in the range from 2.3 to 6 eV, in accordance with constrained local-density approximation [15,16,17] and constrained random-phase approximation [18,19] calculations (see Appendix A for a short overview of these methods). In spite of a large spread in the theoretical estimates of U , one may conclude that the ratio U/W in Fe is less than or equal to 1.…”

Section: Introductionmentioning

confidence: 65%

Electronic correlations in dense iron: from moderate pressure to Earth’s core conditions

Pourovskii

2019

J. Phys.: Condens. Matter

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We discuss the role of dynamical many-electron effects in the physics of iron and ironrich solid alloys under applied pressure on the basis of recent ab initio studies employing the dynamical mean-field theory (DMFT). We review in details two particularly interesting regimes: first, a moderate pressure range up to 60 GPa and, second, the ultra-high pressure of about 360 GPa expected inside the solid inner core of Earth.Electronic correlations in iron under the moderate pressure of several tens GPa are discussed in the first section. DMFT-based methods predict an enhancement of electronic correlations at the pressure-induced body-centered cubic α → hexagonal close-packed phase transition. In particular, the electronic effective mass, scattering rate and electron-electron contribution to the electrical resistivity undergo a step-wise increase at the transition point. One also finds a significant many-body correction to the -Fe equation of state, thus clarifying the origin of discrepancies between previous DFT studies and experiment. An electronic topological transition is predicted to be induced in -Fe by many-electron effects; its experimental signatures are analyzed.Next section focuses on the geophysically relevant pressure-temperature regime of the Earth's inner core (EIC) corresponding to the extreme pressure of 360 GPa combined with temperatures up to 6000 K. The three iron allotropes (α, and face-centered-cubic γ) previously proposed as possible stable phases at such conditions are found to exhibit qualitatively different many-electron effects as evidenced by a strongly non-Fermi-liquid metallic state of α-Fe and an almost perfect Fermi liquid in the case of -Fe. A recent active discussion on the electronic state and transport properties of -Fe at the EIC conditions is reviewed in details. Estimations for the dynamical many-electron contribution to the relative phase stability are presented. We also discuss the impact of a Ni admixture, which is expected to be present in the core matter. We conclude by outlining some limitation of the present DMFTbased framework relevant for studies of iron-base systems as well as perspective directions for further development.

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“…1(a) the evolution with temperature of the mean value of the magnitude of the local Fe moments, as they are a key ingredient in many magnetic theories and studies on Fe-based systems, both in historically pioneering studies [54][55][56] and in recent works (see, e.g., Refs. [3,5,[9][10][11][12][13][14]17,57,58]). …”

Section: A Average Local Magnetic Momentsmentioning

confidence: 99%

“…On the other hand, Igoshev et al performed LDA+DMFT calculations and found that m 2 z of bcc Fe decreased at high temperature [11]. Both the effective local moments and the obtained critical temperature of DMFT calculations depend heavily on the parameters U and J [13]. All DMFT calculations so far have been done assuming an ideal lattice, thus neglecting vibrationally induced disorder.…”

Section: A Average Local Magnetic Momentsmentioning

confidence: 99%

“…With the advent of high performance computational resources, advanced first-principles techniques can now be applied to study the magnetic and electronic structure of Fe at elevated temperature. These include the dynamical mean field theory (DMFT) [5,[8][9][10][11][12][13][14], Hubbard models [15], the dynamical coherent potential approximation [16], extended Heisenberg models based on parameters calculated with density functional theory [17][18][19][20][21], spin cluster expansions [22][23][24], or spin-fluctuation theory [6]. For an overview of the recent advances in this field see, e.g., Refs.…”

Section: Introductionmentioning

confidence: 99%

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Strong impact of lattice vibrations on electronic and magnetic properties of paramagnetic Fe revealed by disordered local moments molecular dynamics

et al. 2016

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We study the impact of lattice vibrations on magnetic and electronic properties of paramagnetic bcc and fcc iron at finite temperature, employing the disordered local moments molecular dynamics (DLM-MD) method. Vibrations strongly affect the distribution of local magnetic moments at finite temperature, which in turn correlates with the local atomic volumes. Without the explicit consideration of atomic vibrations, the mean local magnetic moment and mean field derived magnetic entropy of paramagnetic bcc Fe are larger compared to paramagnetic fcc Fe, which would indicate that the magnetic contribution stabilizes the bcc phase at high temperatures. In the present study we show that this assumption is not valid when the coupling between vibrations and magnetism is taken into account. At the γ -δ transition temperature (1662 K), the lattice distortions cause very similar magnetic moments of both bcc and fcc structures and hence magnetic entropy contributions. This finding can be traced back to the electronic densities of states, which also become increasingly similar between bcc and fcc Fe with increasing temperature. Given the sensitive interplay of the different physical excitation mechanisms, our results illustrate the need for an explicit consideration of vibrational disorder and its impact on electronic and magnetic properties to understand paramagnetic Fe. Furthermore, they suggest that at the γ -δ transition temperature electronic and magnetic contributions to the Gibbs free energy are extremely similar in bcc and fcc Fe.

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Coulomb interaction parameters in bcc iron: an LDA+DMFT study

Cited by 32 publications

References 86 publications

Electron–electron scattering and thermal conductivity ofϵ-iron at Earth’s core conditions

Electron–electron scattering and thermal conductivity ofϵ-iron at Earth’s core conditions

Electronic correlations in dense iron: from moderate pressure to Earth’s core conditions

Strong impact of lattice vibrations on electronic and magnetic properties of paramagnetic Fe revealed by disordered local moments molecular dynamics

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