A systematic determination of hubbard U using the GBRV ultrasoft pseudopotential set

Bennett, Joseph W.; Hudson, Blake G.; Metz, Irene K.; Liang, Dongyue; Spurgeon, Sidney; Cui, Qiang; Mason, Sara E.

doi:10.1016/j.commatsci.2019.109137

Cited by 42 publications

(26 citation statements)

References 75 publications

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“…Next, in the case of d 0 TM-containing materials, the U values computed for the partially occupied d states were applied to either 3d, 4d, or 5d states depending on the TM period in the periodic table. In general, the smaller the principal quantum number the larger the localization of the d orbitals (because they are closer to the nucleus); thus, the value of U is expected to be larger for 3d states than for 4d and 5d states [117]. Indeed, we see this trend for the U values of the TM d 0 elements in Table 2.…”

Section: Hubbard U Parameters From First Principlesmentioning

confidence: 60%

Extensive Benchmarking of DFT+U Calculations for Predicting Band Gaps

et al. 2021

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Accurate computational predictions of band gaps are of practical importance to the modeling and development of semiconductor technologies, such as (opto)electronic devices and photoelectrochemical cells. Among available electronic-structure methods, density-functional theory (DFT) with the Hubbard U correction (DFT+U) applied to band edge states is a computationally tractable approach to improve the accuracy of band gap predictions beyond that of DFT calculations based on (semi)local functionals. At variance with DFT approximations, which are not intended to describe optical band gaps and other excited-state properties, DFT+U can be interpreted as an approximate spectral-potential method when U is determined by imposing the piecewise linearity of the total energy with respect to electronic occupations in the Hubbard manifold (thus removing self-interaction errors in this subspace), thereby providing a (heuristic) justification for using DFT+U to predict band gaps. However, it is still frequent in the literature to determine the Hubbard U parameters semiempirically by tuning their values to reproduce experimental band gaps, which ultimately alters the description of other total-energy characteristics. Here, we present an extensive assessment of DFT+U band gaps computed using self-consistent ab initioU parameters obtained from density-functional perturbation theory to impose the aforementioned piecewise linearity of the total energy. The study is carried out on 20 compounds containing transition-metal or p-block (group III-IV) elements, including oxides, nitrides, sulfides, oxynitrides, and oxysulfides. By comparing DFT+U results obtained using nonorthogonalized and orthogonalized atomic orbitals as Hubbard projectors, we find that the predicted band gaps are extremely sensitive to the type of projector functions and that the orthogonalized projectors give the most accurate band gaps, in satisfactory agreement with experimental data. This work demonstrates that DFT+U may serve as a useful method for high-throughput workflows that require reliable band gap predictions at moderate computational cost.

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Section: Hubbard U Parameters From First Principlesmentioning

confidence: 60%

Extensive Benchmarking of DFT+U Calculations for Predicting Band Gaps

et al. 2021

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“…Several approaches exist for estimating the correct U values from first‐principles calculations, for example by using a linear response approach or from constrained random phase approximation calculations . Nevertheless, the U values estimated by these methods often do not fully correct the band gap problem and thus, it is not clear what value of U must be used to obtain accurate band gaps values.…”

Section: Methodological Developmentsmentioning

confidence: 99%

First‐principles Studies of Band Gap Engineering in Ferroelectric Oxides

Grinberg

2020

Israel Journal of Chemistry

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In the last decade there has been a resurgence of activity in the field of photoferroelectrics with a focus on the studies of oxides. Ferroelectric (FE) materials have a spontaneous switchable polarization that can lead to interesting light-matter interactions such as the bulk photovoltaic effect. While a wide range of compositions has been explored for ferroelectrics, until recently, FE oxides were considered to be capable of absorbing UV light only. Playing a key role in the advance of the field, first-principles calculations have guided the experimental materials discovery efforts that have identified a wide variety of visible-light-absorbing oxides. First-principles research efforts have also achieved considerable progress in revealing the interplay between the composition, structure and light absorption properties in these materials, and it is now understood that even small changes in the local environment can lead to large changes in band gap character and magnitude. Here, we survey the first-principles efforts following different band-gap engineering strategies and the advances in the computational methods that have been driven by these studies.

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“…The level of DFT that is used here has been shown to underestimate the bandgaps, but has been shown previously to capture the qualitative trends we are studying. 35,36 All atoms are represented as ultrasoft GBRV-type pseudopotentials, 37,38 and all calculations use a plane-wave cutoff of 40 Ry for the wavefunction and 320 Ry for the charge density. The convergence criterion for self-consistent relaxations was a maximum residual force of 5 meV/Å per atom, and all atoms are allowed to relax during structural optimizations.…”

Section: Methodsmentioning

confidence: 99%

First-Principles and Thermodynamics Comparison of Compositionally-Tuned Delafossites: Cation Release from the (001) Surface of Complex Metal Oxides

Bennett¹,

Jones

Hudson³

et al. 2019

Preprint

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Nanoscale complex metal oxides have transformed how technology is used around the world. A ubiquitous example is the class of electroreactive cathodes used in Li-ion batteries, found in portable electronics and electric cars. Lack of recyling infrasructure and financial drivers contribute to improper disposal, and ultimate introduction of these materials into the environment. Outside of sealed operational conditions, it has been demonstrated that complex metal oxides can transform in the environment, and cause negative biological impact through leaching of cations into aqueous phases. Using a combined DFT + Thermodynamics analysis, insights into the mechanism and driving forces of cation release can be studied at the molecular-level. Here, we describe design principles that can be drawn from previous collaborative research on complex metal oxide dissoltuion of the Li(NiyMnzCo1−y−z)O2 family of materials, and go on to posit ternary complex metal oxides in the delafossite structure type with controlled release behavior. Using equistoichiometric formulations, we use DFT + Thermodynamics to model cation release. The trends are discussed in terms of lattice stability, solution chemistry/solubility limits, and electronic/magnetic properties. Inercalation voltages are calculated and discussed as a predictive metric for potential functionality of the model materials.

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A systematic determination of hubbard U using the GBRV ultrasoft pseudopotential set

Cited by 42 publications

References 75 publications

Extensive Benchmarking of DFT+U Calculations for Predicting Band Gaps

Extensive Benchmarking of DFT+U Calculations for Predicting Band Gaps

First‐principles Studies of Band Gap Engineering in Ferroelectric Oxides

First-Principles and Thermodynamics Comparison of Compositionally-Tuned Delafossites: Cation Release from the (001) Surface of Complex Metal Oxides

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