Unraveling the effects of inter-site Hubbard interactions in spinel Li-ion cathode materials

Timrov, Iurii; Kotiuga, Michele; Marzari, Nicola

doi:10.1039/d3cp00419h

Cited by 6 publications

(4 citation statements)

References 102 publications

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“…By doing so, we obtain structural parameters that are optimized using PBEsol+U and PBEsol+U +V using the respective self-consistent Hubbard parameters and that are listed in Table I. This methodology has demonstrated its efficacy in yielding accurate results for various transition-metal compounds [73][74][75][76][77][78][79][80]. The computed values of the Hubbard parameters are as follows: U = 4.52 eV for Ti(3d) states within PBEsol+U and U = 5.21 eV for Ti(3d) states with intersite V values ranging from 1.17 to 1.37 eV (depending on the interatomic distance) between Ti(3d) and O(2p) states within PBEsol+U +V .…”

Section: Computational Detailsmentioning

confidence: 99%

Understanding the role of Hubbard corrections in the rhombohedral phase of BaTiO3

Gebreyesus,

Bastonero,

Kotiuga

et al. 2023

Phys. Rev. B

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We present a first-principles study of the low-temperature rhombohedral phase of BaTiO 3 using Hubbardcorrected density-functional theory. By employing density-functional perturbation theory, we compute the onsite Hubbard U for Ti(3d) states and the intersite Hubbard V between Ti(3d) and O(2p) states. We show that applying the onsite Hubbard U correction alone to Ti(3d) states proves detrimental, as it suppresses the Ti(3d)-O(2p) hybridization and drives the system towards a cubic phase. Conversely, when both onsite U and intersite V are considered, the localized character of the Ti(3d) states is maintained, while also preserving the Ti(3d)-O(2p) hybridization, restoring the rhombohedral phase of BaTiO 3 . The generalized PBEsol+U +V functional yields good agreement with experimental results for the band gap and dielectric constant, while the optimized geometry is slightly less accurate compared to PBEsol. Zone-center phonon frequencies and Raman spectra are found to be significantly influenced by the underlying geometry. PBEsol and PBEsol+U +V provide satisfactory agreement with the experimental Raman spectrum when the PBEsol geometry is used, while PBEsol+U Raman spectrum diverges strongly from experimental data highlighting the adverse impact of the U correction alone in BaTiO 3 . Our findings underscore the promise of the extended Hubbard PBEsol+U +V functional with first-principles U and V for the investigation of other ferroelectric perovskites with mixed ionic-covalent interactions.

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Section: Computational Detailsmentioning

confidence: 99%

Understanding the role of Hubbard corrections in the rhombohedral phase of BaTiO3

Gebreyesus,

Bastonero,

Kotiuga

et al. 2023

Phys. Rev. B

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“…Some authors have explored including ligand orbitals in the on-site Hubbard manifold, for example applying U corrections to O- p and S- p shells of TM compounds. ,,− The extended DFT+ U + V framework was adopted for scenarios where hybridization plays an eminent role. This method augments DFT+ U by an intersite Hubbard V term, and so acts on combinations of projectors located on different sites, enhancing accuracy and transferability. ,,− Finally, many open-shell systems require unlike-spin terms such as Hund’s J . In DFT+ U + J , these terms introduce an unlike-spin exchange correction, while also reducing the effective value of the U parameter. ,,,, It remains to be shown in how far a single-determinant method such as DFT+ U (+ J ) suffices to adequately describe compounds with a strong multireference character, but it is likely that Hubbard U and Hund’s J corrections can improve the description of approximate single-determinant solutions to multiconfigurational systems , (often obtained by breaking the symmetry).…”

Section: Introductionmentioning

confidence: 99%

Orbital-Resolved DFT+U for Molecules and Solids

Macke,

Timrov,

Marzari

et al. 2024

J. Chem. Theory Comput.

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We present an orbital-resolved extension of the Hubbard U correction to density-functional theory (DFT). Compared to the conventional shell-averaged approach, the prediction of energetic, electronic and structural properties is strongly improved, particularly for compounds characterized by both localized and hybridized states in the Hubbard manifold. The numerical values of all Hubbard parameters are readily obtained from linear-response calculations. The relevance of this more refined approach is showcased by its application to bulk solids pyrite (FeS2) and pyrolusite (β-MnO2), as well as to six Fe(II) molecular complexes. Our findings indicate that a careful definition of Hubbard manifolds is indispensable for extending the applicability of DFT+U beyond its current boundaries. The present orbital-resolved scheme aims to provide a computationally undemanding yet accurate tool for electronic structure calculations of charge-transfer insulators, transition-metal (TM) complexes and other compounds displaying significant orbital hybridization.

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“…This is followed by a demonstration of the effectiveness of the approach in achieving even exotic target occupations and oxidation states. The ability of controlling oxidation states 44 – 46 opens the door to investigations of electron-transfer excitations 47 , compounds with mixed valence 48 – 50 or charge disproportionation such as skutterudites 51 – 58 or, e.g., LiR 2 O 4 spinels with R = ( M n , F e ) that are of interest as cathodes in batteries 59 , 60 . We then explore extensively the energy landscape in NiO, a prototype magnetic oxide, by utilizing a global minimization technique.…”

Section: Introductionmentioning

confidence: 99%

The energy landscape of magnetic materials

Ponet,

Di Lucente,

Marzari

2024

npj Comput Mater

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Magnetic materials can display many solutions to the electronic-structure problem, corresponding to different local or global minima of the energy functional. In Hartree-Fock or density-functional theory different single-determinant solutions lead to different magnetizations, ionic oxidation states, hybridizations, and inter-site magnetic couplings. The vast majority of these states can be fingerprinted through their projection on the atomic orbitals of the magnetic ions. We have devised an approach that provides an effective control over these occupation matrices, allowing us to systematically explore the landscape of the potential energy surface. We showcase the emergence of a complex zoology of self-consistent states; even more so when semi-local density-functional theory is augmented - and typically made more accurate - by Hubbard corrections. Such extensive explorations allow to robustly identify the ground state of magnetic systems, and to assess the accuracy (or not) of current functionals and approximations.

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Unraveling the effects of inter-site Hubbard interactions in spinel Li-ion cathode materials

Abstract: Accurate first-principles predictions of the structural, electronic, magnetic, and electrochemical properties of cathode materials can be key in the design of novel efficient Li-ion batteries. Spinel-type cathode materials Li$_x$Mn$_2$O$_4$ and...

Cited by 6 publications

References 102 publications

Understanding the role of Hubbard corrections in the rhombohedral phase of BaTiO3

Understanding the role of Hubbard corrections in the rhombohedral phase of BaTiO3

Orbital-Resolved DFT+U for Molecules and Solids

The energy landscape of magnetic materials

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