Electron delocalization and the characterization of the<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msub><mml:mrow><mml:mi>L</mml:mi></mml:mrow><mml:mrow><mml:mn>3</mml:mn></mml:mrow></mml:msub></mml:mrow><mml:mi>MM</mml:mi></mml:math>Auger spectra of<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mn>3</mml:mn><mml:mi>d</mml:mi></mml:math>transition metals

Yin, L.; Tsang, Tung; Adler, I.

doi:10.1103/physrevb.15.2974

Cited by 92 publications

(17 citation statements)

References 33 publications

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“…The difference in energy between the nickel d-band centroid and the satellite should be equal to that between the energies of the final states with d 9 and d 8 configurations, which depends on the energy of interaction of two holes in the nickel d band which are localized on one atom in the d 8 configuration, and on the relaxation energy of the d 8 final state [37,38]. In XPS spectra of Ti-Ni alloys, the nickel satellite lies farther in energy with respect to the nickel d-band centroid compared with Ni.…”

Section: Discussionmentioning

confidence: 99%

Electronic structure of Ti–Ni alloys: An XPS and NEXAFS study

Senkovskiy

Usachov

Fedorov

et al. 2012

Journal of Alloys and Compounds

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Section: Discussionmentioning

confidence: 99%

Electronic structure of Ti–Ni alloys: An XPS and NEXAFS study

Senkovskiy

Usachov

Fedorov

et al. 2012

Journal of Alloys and Compounds

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“…Experimentally, the Hubbard U parameters for 3d TMs are deduced from a combined use of Auger and x-ray photoemission spectroscopy. [19][20][21] Results from three different groups are included in Fig. 2 for comparison.…”

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confidence: 99%

Effective Coulomb interaction in transition metals from constrained random-phase approximation

2011

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The effective on-site Coulomb interaction (Hubbard U ) between localized d electrons in 3d, 4d, and 5d transition metals is calculated employing a parameter-free realization of the constrained random-phase approximation using Wannier functions within the full-potential linearized augmented-plane-wave method. The U values lie between 1.5 and 5.7 eV and depend on the crystal structure, spin polarization, d electron number, and d orbital filling. On the basis of the calculated U parameters, we discuss the strength of the electronic correlations and the instability of the paramagnetic state toward the ferromagnetic one for 3d metals. 3 However, in these models the Coulomb and also the one-particle hopping matrix elements are typically empirical parameters that are determined such that the employed model reproduces experimental results of interest.For a long time, DFT-LDA and many-body model Hamiltonian methods have been separate and complementary approaches. This has drastically changed with the advent of the dynamical mean-field theory (DMFT), 4 which merged with the LDA to become a novel computational method referred to as LDA + DMFT, 5 which developed into a modern many-body approach for treating correlated electron materials. In retrospect, the so-called LDA + U method, 6 an early attempt to correct the LDA functional by introducing a simple mean-field-like Hubbard U term for localized d or f states, and today routinely applied to a broad spectrum of systems, can be regarded as its static limit. Both LDA + U and LDA + DMFT as well as other approaches not mentioned here rely on the Hubbard U as an additional parameter. Frequently, the exact value of U is unknown, which impedes the predictive power of these approaches.The problem of calculating the parameter-free Hubbard U for transition metals (TMs), i.e., from first principles, has been addressed by several authors.7-11 A number of different approaches have been proposed. Among them, the constrained local-density approximation (cLDA) 9 is the most popular. However, the cLDA is known to give unreasonably large U values for late TMs due to difficulties in compensating for the self-screening error of the localized electrons.10 Furthermore, the frequency dependence of U is unattainable. On the other hand, the constrained random-phase approximation (cRPA), though numerically much more demanding, does not suffer from these difficulties. In contrast to the cLDA, it also allows access to individual Coulomb matrix elements, e.g., on-site, off-site, intra-orbital, interorbital, and exchange.The aim of this Rapid Communication is to present a systematic study of the effective on-site Coulomb interaction (Hubbard U) between localized d electrons in TMs determined by means of first-principles calculations. Previous cRPA studies of U in TMs have focused only on the nonmagnetic (NM) state of the 3d series, and the results appeared to be strongly dependent on the parameters used in the cRPA schemes. 10,11 In the present work, we propose an alternative simple parameter-free c...

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“…A more detailed comparison with the U expt 's requires to calculate ab ini- ) expt and Ref. [6] for U (2) expt .…”

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First-principles calculation of effective onsite Coulomb interactions of3dtransition metals: Constrained local density functional approach with maximally localized Wannier functions

et al. 2006

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We present a new ab initio method for calculating effective onsite Coulomb interactions of itinerant and strongly correlated electron systems. The method is based on constrained local density functional theory formulated in terms of maximally localized Wannier functions. This scheme can be implemented with any basis, and thus allows us to perform the constrained calculation with plane-wave-based electronic-structure codes. We apply the developed method to the evaluation of the onsite interaction of 3d transition-metal series. The results are discussed using a heuristic formula for screened Coulomb interactions.Properties of itinerant and strongly correlated electron systems are widely discussed with phenomenological Hamiltonians such as Anderson-impurity [1] and Hubbard models [2]. These models embody essential aspects of correlated electrons, and can be solved numerically or sometimes analytically for special cases. However, parameters in the models are often determined empirically so that the employed model should reproduce experimental results of interest.Recently, there has been growing interest in constructing model Hamiltonians from first principles [3]. The principal motivation for such a study is a so-called long-standing "beyond LDA" problem. One of recent major approaches toward correlated electrons from first principles is combining densityfunctional theory within local density approximation (LDA) with dynamical mean-field theory (DMFT) [4]. The main idea of this method is to map a first-principles Hamiltonian onto a lattice-fermion model to which the DMFT method is applicable, so developments of tractable but rational mapping techniques are highly needed.An important notice in constructing ab initio model Hamiltonians lies in an evaluation of an onsite interaction parameter known as the Hubbard U . Transfer parameters can be easily obtained by representing a one-body ab initio Hamiltonian with a spatially localized (or atomic) orbital, while the U parameter evaluated with a one-center Coulomb integral of the atomic orbital gives a rather large value relative to that deduced from experiments [5,6]. This is because a screening effect of surrounding valence electrons is completely neglected in the evaluation of the value. A representative treatment for calculating U including the screening effect is a constrained approach [7,8]. It gives an optimally screened U , because, in that calculation, the U value is obtained from a response of the system to a change in a local charge density, thus incorporating the valence-electron-screening effect statically into the U calculation.An important point in performing the constrained calculation is a choice of basis functions to define the charge density of localized electrons. The use of an atom-centered localized basis set like a linear muffin-tin orbital (LMTO) [9] facilitates this definition, so constrained calculations to date have been performed with LMTO-based electronic-structure codes. The method has been widely applied to investigations of effective Hubbar...

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Electron delocalization and the characterization of theL3MMAuger spectra of3dtransition metals

Cited by 92 publications

References 33 publications

Electronic structure of Ti–Ni alloys: An XPS and NEXAFS study

Electronic structure of Ti–Ni alloys: An XPS and NEXAFS study

Effective Coulomb interaction in transition metals from constrained random-phase approximation

First-principles calculation of effective onsite Coulomb interactions of3dtransition metals: Constrained local density functional approach with maximally localized Wannier functions

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