TRIQS/DFTTools: A TRIQS application for ab initio calculations of correlated materials

Aichhorn, Markus; Pourovskii, L. V.; Seth, Priyanka; Vildosola, V.; Zingl, Manuel; Peil, Oleg E.; Deng, Xiaoyu; Mravlje, Jernej; Kraberger, Gernot J.; Martins, Cyril; Ferrero, Michel; Parcollet, Olivier

doi:10.1016/j.cpc.2016.03.014

Cited by 161 publications

(141 citation statements)

References 41 publications

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“…We employ the DFT+Hub-I approach 47 based on the TRIQS library 48 and the full potential linearized augmented planewave Wien-2k…”

Section: B Calculational Approachmentioning

confidence: 99%

“…Wannier orbitals constructed with a "small window" leak 47 to neighboring sites due to hybridization between 4f states and conduction band states. A larger window results in more localized Wannier orbitals consisting almost exclusively of the corresponding 4f partial waves inside the rare-earth atomic sphere, 47,51 as discussed in in Sec. IV and Appendix E below.…”

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confidence: 99%

“…Hence we also directly remove the 4f spin polarization from the resulting DFT+Hub-I density matrix. For a given kpoint the "averaged" density matrixÑ k in the Bloch basis reads: (10) where N k is the density matrix in the Bloch basis calculated as described in Refs.54 and47, P (k) is the projector 47,51 between the Wannier and Bloch spaces, n f f (k) is the density matrix in the Wannier basis, T is the time-reversal operator. The averaged density matrixÑ k is then used to recalculate the electron density at the next DFT iteration as described in Ref.…”

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confidence: 99%

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Crystal-field splittings in rare-earth-based hard magnets: Anab initioapproach

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Biermann

Miyake³

et al. 2017

Phys. Rev. B

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We apply the first-principles density functional theory + dynamical mean field theory framework to evaluate the crystal-field splitting on rare-earth sites in hard magnetic intermetallics. An atomic (Hubbard-I) approximation is employed for local correlations on the rare-earth 4f shell and selfconsistency in the charge density is implemented. We reduce the density functional theory selfinteraction contribution to the crystal-field splitting by properly averaging the 4f charge density before recalculating the one-electron Kohn-Sham potential. Our approach is shown to reproduce the experimental crystal-field splitting in the prototypical rare-earth hard magnet SmCo5. Applying it to RFe12 and RFe12X hard magnets (R =Nd, Sm and X =N, Li), we obtain in particular a large positive value of the crystal-field parameter A 0 2 r 2 in NdFe12N resulting in a strong out-of-plane anisotropy observed experimentally. The sign of A 0 2 r 2 is predicted to be reversed by substituting N with Li, leading to a strong out-of-plane anisotropy in SmFe12Li. We discuss the origin of this strong impact of N and Li interstitials on the crystal-field splitting on rare-earth sites.

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“…We employ the DFT+Hub-I approach 47 based on the TRIQS library 48 and the full potential linearized augmented planewave Wien-2k…”

Section: B Calculational Approachmentioning

confidence: 99%

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confidence: 99%

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confidence: 99%

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Crystal-field splittings in rare-earth-based hard magnets: Anab initioapproach

Delange

Biermann

Miyake³

et al. 2017

Phys. Rev. B

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“…Our calculations have been carried out using a fully charge self-consistent implementation of DFT+DMFT [53,54] based on the TRIQS package [55,56], with LDA as DFT exchangecorrelation potential. This implementation is based on the full potential linearized augmented plane-wave WIEN2K code [57].…”

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confidence: 99%

Large effects of subtle electronic correlations on the energetics of vacancies inα-Fe

et al. 2016

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We study the effect of electronic Coulomb correlations on the vacancy formation energy in paramagnetic α-Fe within ab initio dynamical mean-field theory. The calculated value for the formation energy is substantially lower than in standard density-functional calculations and in excellent agreement with experiment. The reduction is caused by an enhancement of electronic correlations at the nearest neighbors of the vacancy. This effect is explained by subtle changes in the corresponding spectral function of the d electrons. The local lattice relaxations around the vacancy are substantially increased by many-body effects. DOI: 10.1103/PhysRevB.94.100102 Point defects, such as vacancies, play an important role for the mechanical and thermodynamic properties of materials [1]. However, the experimental determination of vacancy formation or migration energies is difficult. Even the best available techniques, the differential dilatometry and the positron annihilation spectroscopy, suffer from large error bars, and the discrepancies between different measurements on one and the same material may be significant. Therefore, ab initio theoretical calculations are an indispensable tool for developing a better understanding of the defect properties of materials [2].Early density-functional theory (DFT) calculations in the local density approximation (LDA) have predicted formation energies of vacancies in simple metals in good agreement with experiment [3,4]. Despite a large body of successful calculations, it has later been recognized that the nice agreement with experiment could often be the effect of the cancellation of errors in the exchange and correlation parts of the density functional [5]. As has been discussed by Ruban [6], despite the structural simplicity of vacancies, their energetics is still one of the least reliable physical properties determined in first-principles calculations.In transition metals, where the open d shells are often poorly described in LDA or the generalized gradient approximation (GGA), the quality of results of DFT calculations for point defect properties is rather unpredictable and strongly material dependent. There have been several attempts to improve the available functionals (see, e.g., Refs. [7][8][9][10]). We notice that the predicted vacancy formation energies seem to be especially poor for 3d transition metals, for which many-body effects are fairly important, in particular in the paramagnetic state and body-centered cubic (bcc) crystal structure [11]. Likewise, DFT has limitations for point defect calculations in correlated lanthanide or actinide oxides with 4f or 5f electrons, for example in the case of uranium oxides used in the nuclear industry [12].Among the 3d transition metals, iron is a particularly complex system, where the strength of electronic correlations is very sensitive to the lattice structure and magnetic state. However, from a practical point of view, vacancies in iron and steels are of particular interest because they affect a number of important characteristic...

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“…29 The V 3d subspace for the DMFT treatment was constructed from the allelectron electronic structure using the triqs/dfttools package. 30,31 The local Hamiltonian of the V 3d subspace has large off-diagonal elements, and the use of the continuous-time hybridization-expansion Monte Carlo solver triqs/cthyb written by Seth and Krivenko ameliorated the sign problem. 32,33 The calculations were done at an inverse temperature of β = 23 eV −1 (k B T 500 K > T t ).…”

Section: Computational Detailsmentioning

confidence: 99%

Mott-to-Goodenough insulator-insulator transition inLiVO2

Subedi

2017

Phys. Rev. B

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TRIQS/DFTTools: A TRIQS application for ab initio calculations of correlated materials

Cited by 161 publications

References 41 publications

Crystal-field splittings in rare-earth-based hard magnets: Anab initioapproach

Crystal-field splittings in rare-earth-based hard magnets: Anab initioapproach

Large effects of subtle electronic correlations on the energetics of vacancies inα-Fe

Mott-to-Goodenough insulator-insulator transition inLiVO2

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