Importance of intersite Hubbard interactions in 
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: A first-principles 
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 study

Mahajan, Ruchika; Timrov, Iurii; Marzari, Nicola; Kashyap, Arti

doi:10.1103/physrevmaterials.5.104402

Cited by 22 publications

(59 citation statements)

References 95 publications

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“…[10]. In fact, by constructing the localized perturbation (typically requiring costly calculations in supercells) as a series of independent monochromatic perturbations in the primitive unit cell, it improves significantly the computational efficiency, accuracy, user-friendliness, and automation [2,3], as also demonstrated by several recent applications [14,41,15,42,43,44,45,46,47,48,49]. Key to this successful implementation of the LR-cDFT is indeed the capability to express perturbation theory in reciprocal space as in the calculation of phonons using DFPT [50,51,52].…”

Section: Introductionmentioning

confidence: 94%

HP -- A code for the calculation of Hubbard parameters using density-functional perturbation theory

Timrov,

Marzari,

Cococcioni

2022

Preprint

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We introduce HP, an implementation of density-functional perturbation theory, designed to compute Hubbard parameters (on-site U and inter-site V) in the framework of DFT+U and DFT+U+V. The code does not require the usage of computationally expensive supercells of the traditional linear-response approach; instead, unit cells are used with monochromatic perturbations that significantly reduces the computational cost of determining Hubbard parameters. HP is open-source software distributed under the terms of the GPL as a component of Quantum ESPRESSO . As with other components, HP is optimized to run on a variety of different platforms, from laptops to massively parallel architectures, using native mathematical libraries (LAPACK and FFTW) and a hierarchy of custom parallelization layers built on top of MPI. The effectiveness of the code is showcased by computing Hubbard parameters self-consistently for the phospho-olivine Li x Mn 1/2 Fe 1/2 PO 4 (x = 0, 1/2, 1) and by highlighting the accuracy of predictions of the geometry and intercalation voltages.

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Section: Introductionmentioning

confidence: 94%

HP -- A code for the calculation of Hubbard parameters using density-functional perturbation theory

Timrov,

Marzari,

Cococcioni

2022

Preprint

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“…With this choice of projector functions the electrons in the intersite overlap regions are not counted twice when computing the atomic occupations used in the Hubbard correction, as it is instead the case for the nonorthogonalized atomic orbitals φ I m (r). As a matter of fact, DFT+Hubbard with the Löwdin orthogonalized orbitals have proven to give more accurate results for various properties of materials [67][68][69][70][71][72], provided the Hubbard parameters are consistently computed with the Löwdin orthogonalized orbitals. Therefore, Hubbard parameters and Hubbard projectors should always be defined consistently and reported together.…”

Section: A Dft+hubbardmentioning

confidence: 99%

Accurate electronic properties and intercalation voltages of olivine-type Li-ion cathode materials from extended Hubbard functionals

Timrov¹,

Aquilante²,

Cococcioni³

et al. 2022

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The design of novel cathode materials for Li-ion batteries requires accurate first-principles predictions of structural, electronic, and magnetic properties as well as intercalation voltages in compounds containing transition-metal (TM) elements. For such systems, density-functional theory (DFT) with standard (semi-)local exchange-correlation functionals is of no use as it fails dramatically due to strong self-interaction (delocalization) errors for the partially filled d shells of the TMs. Here, we perform the first comparative study of the phospho-olivine cathode materials LixMnPO4, LixFePO4, and mixed-TM LixMn 1/2 Fe 1/2 PO4 (x = 0, 1/4, 1/2, 3/4, 1) using four electronic structure methods: DFT, DFT+U , DFT+U +V , and HSE06. We show that DFT+U +V outperforms the other three methods, provided that the on-site U and intersite V Hubbard parameters are determined from first-principles and self-consistently with respect to the structural parameters by means of densityfunctional perturbation theory (linear response). In particular, we demonstrate that DFT+U +V is the only method that correctly predicts the digital change in oxidation states of the TM ions in all compounds for the mixed-valence phases occurring at intermediate Li concentrations, leading to voltages in remarkable agreement with experiments. We thus show that the inclusion of intersite Hubbard interactions is essential for the accurate prediction of thermodynamic quantities when electronic localization occurs while in the presence of inter-atomic orbital hybridization. At variance with the other methods, DFT+U +V alone is capable to describe such localization-hybridization interplay, and thus opens the door for the study of more complex cathode materials as well as for a reliable exploration of the chemical space of compounds for Li-ion batteries.

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“…In particular, in Ref. [50] we have shown that the most accurate description of the structural, electronic, and magnetic properties of β-MnO 2 is obtained using Löwdin-orthogonalized atomic orbitals as Hubbard projectors.…”

Section: B Hubbard Parameters From Dfptmentioning

confidence: 99%

“…In the vast majority of the DFT+U studies of α-MnO 2 , the U parameter is chosen empirically in the range from 1 to 6 eV [39,40,45] such that DFT+U reproduces well some experimental property of interest (e.g., the band gap) [47]. However, when selecting U empirically, it is often forgotten to pay attention also to the type of the Hubbard projectors that are used in various electronic-structure codes, as indeed the DFT+U results are extremely sensitive not only to the value of U but also to the type of these projectors [48][49][50]. Only in one DFT+U study of α-MnO 2 so far the value of U was computed from first principles (using the constrained DFT) [14], though no information is provided regarding the magnetic ordering used.…”

Section: Introductionmentioning

confidence: 99%

“…Therefore, a consistent comparison of the FM and various types of AFM orderings in the pristine and Fe-doped α-MnO 2 using first-principles Hubbard parameters have not been performed so far. Moreover, in all previous Hubbardcorrected DFT studies only the onsite Hubbard U correction was included, while the intersite Hubbard interactions were fully disregarded even though they are known to be very important in MnO 2 polymorphs due to strong Mn(3d)-O(2p) hybridization [50].…”

Section: Introductionmentioning

confidence: 99%

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Electronic structure and magnetism of pristine and Fe-doped $α$-MnO$_2$ from density-functional theory with extended Hubbard functionals

Mahajan,

Kashyap,

Timrov

2022

Preprint

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We present a first-principles investigation of the structural, electronic, and magnetic properties of the pristine and Fe-doped α-MnO2 using density-functional theory with extended Hubbard functionals. The onsite U and intersite V Hubbard parameters are determined from first principles and self-consistently using density-functional perturbation theory in the basis of Löwdin-orthogonalized atomic orbitals. Among the ferromagnetic and four types of antiferromagnetic (AFM) orderings for the pristine α-MnO2 we find the C2-AFM spin configuration to be the most energetically favorable, in agreement with the experimentally observed AFM state. The computed lattice parameters, magnetic moments, and band gaps are overall in good agreement with the experimental ones when both the onsite and intersite Hubbard corrections are included. For the Fe-doped α-MnO2 two types of doping are considered: Fe insertion in the 2 × 2 tunnels and partial substitution of Fe for Mn. The calculated formation energies show that Fe insertion is energetically favorable, in agreement with experiments. We find that both types of doping preserve the C2-AFM spin configuration of the host lattice. The oxidation state of Fe is found to be 2+ and 4+ in the case of the interstitial and substitutional doping, respectively, while the oxidation state of Mn is 4+ in both cases. This work opens a door for accurate studies of other Mn oxides and complex transition-metal compounds when the localization of 3d electrons occurs in the presence of strong covalent interactions with ligands.

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Importance of intersite Hubbard interactions in β−MnO2 : A first-principles DFT+U+V study

Cited by 22 publications

References 95 publications

HP -- A code for the calculation of Hubbard parameters using density-functional perturbation theory

HP -- A code for the calculation of Hubbard parameters using density-functional perturbation theory

Accurate electronic properties and intercalation voltages of olivine-type Li-ion cathode materials from extended Hubbard functionals

Electronic structure and magnetism of pristine and Fe-doped $α$-MnO$_2$ from density-functional theory with extended Hubbard functionals

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