<i>Ab initio</i>study of the electronic states induced by oxygen vacancies in rutile and anatase<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msub><mml:mrow><mml:mtext>TiO</mml:mtext></mml:mrow><mml:mn>2</mml:mn></mml:msub></mml:mrow></mml:math>

Mattioli, Giuseppe; Filippone, F.; Alippi, Paola; Bonapasta, A. Amore

doi:10.1103/physrevb.78.241201

Cited by 252 publications

(117 citation statements)

References 21 publications

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“…Although these large U values give band gaps close to experiment [73], they are somewhat larger than those calculated in Ref. [84] or used, e.g., in defect calculations [85]. given with respect to the rutile phase.…”

Section: Relative Stability Of Rutile and Anatase Phasesmentioning

confidence: 72%

Hubbard-Ucorrected Hamiltonians for non-self-consistent random-phase approximation total-energy calculations: A study of ZnS,TiO2, and NiO

Patrick

Thygesen

2016

Phys. Rev. B

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In non-self-consistent calculations of the total energy within the random-phase approximation (RPA) for electronic correlation, it is necessary to choose a single-particle Hamiltonian whose solutions are used to construct the electronic density and noninteracting response function. Here we investigate the effect of including a Hubbard-U term in this single-particle Hamiltonian, to better describe the on-site correlation of 3d electrons in the transition metal compounds ZnS, TiO 2 , and NiO. We find that the RPA lattice constants are essentially independent of U , despite large changes in the underlying electronic structure. We further demonstrate that the non-selfconsistent RPA total energies of these materials have minima at nonzero U . Our RPA calculations find the rutile phase of TiO 2 to be more stable than anatase independent of U , a result which is consistent with experiments and qualitatively different from that found from calculations employing U -corrected (semi)local functionals. However we also find that the +U term cannot be used to correct the RPA's poor description of the heat of formation of NiO.

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Section: Relative Stability Of Rutile and Anatase Phasesmentioning

confidence: 72%

Hubbard-Ucorrected Hamiltonians for non-self-consistent random-phase approximation total-energy calculations: A study of ZnS,TiO2, and NiO

Patrick

Thygesen

2016

Phys. Rev. B

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“…The formation of a neutral oxygen vacancy results in two excess electrons in the system, giving rise to the formation of two Ti(III) ions. Although the optimal positions of the Ti(III) ions relative to the oxygen vacancy have been studied in some detail before, 34,[55][56][57] to fully assess the ability of the occupation matrix approach a full assessment of the cell was conducted. Initial tests indicated that the differences in energy between ferromagnetic and antiferromagnetic configurations of the two Ti(III) ions was insignificant, therefore only ferromagnetic couplings were trialled.…”

Section: Timentioning

confidence: 99%

Occupation matrix control of d- and f-electron localisations using DFT + U

Allen

Watson

2014

Phys. Chem. Chem. Phys.

201

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The use of a density functional theory methodology with on-site corrections (DFT + U) has been repeatedly shown to give an improved description of localised d and f states over those predicted with a standard DFT approach. However, the localisation of electrons also carries with it the problem of metastability, due to the possible occupation of different orbitals and different locations. This study details the use of an occupation matrix control methodology for simulating localised d and f states with a plane-wave DFT + U approach which allows the user to control both the site and orbital localisation.This approach is tested for orbital occupation using octahedral and tetrahedral Ti(III) and Ce(III) carbonyl clusters and for orbital and site location using the periodic systems anatase-TiO 2 and CeO 2 . The periodic cells are tested by the addition of an electron and through the formation of a neutral oxygen vacancy (leaving two electrons to localise). These test systems allow the successful study of orbital degeneracies, the presence of metastable states and the importance of controlling the site of localisation within the cell, and it highlights the use an occupation matrix control methodology can have in electronic structure calculations.

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“…The optoelectronic properties of O-deficient TiO 2 (TiO 2−x ) have been extensively investigated both experimentally 47 and theoretically, 15,[48][49][50][51][52][53] making this system an ideal model for testing the performance of the dielectric-dependent hybrid method in describing the electronic properties of defective semiconductors.…”

Section: A Tiomentioning

confidence: 99%

Defect calculations in semiconductors through a dielectric-dependent hybrid DFT functional: The case of oxygen vacancies in metal oxides

Gerosa

Bottani

Caramella

et al. 2015

The Journal of Chemical Physics

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We investigate the behavior of oxygen vacancies in three different metal-oxide semiconductors\ud (rutile and anatase TiO2, monoclinic WO3, and tetragonal ZrO2) using a recently proposed hybrid\ud density-functional method in which the fraction of exact exchange is material-dependent but obtained\ud ab initio in a self-consistent scheme. In particular, we calculate charge-transition levels relative to the\ud oxygen-vacancy defect and compare computed optical and thermal excitation/emission energies with\ud the available experimental results, shedding light on the underlying excitation mechanisms and related\ud materials properties. We find that this novel approach is able to reproduce not only ground-state\ud properties and band structures of perfect bulk oxide materials but also provides results consistent\ud with the optical and electrical behavior observed in the corresponding substoichiometric defective\ud systems. C 2015 AIP Publishing LLC. [http://dx.doi.org/10.1063/1.493180

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Ab initiostudy of the electronic states induced by oxygen vacancies in rutile and anataseTiO2

Cited by 252 publications

References 21 publications

Hubbard-Ucorrected Hamiltonians for non-self-consistent random-phase approximation total-energy calculations: A study of ZnS,TiO2, and NiO

Hubbard-Ucorrected Hamiltonians for non-self-consistent random-phase approximation total-energy calculations: A study of ZnS,TiO2, and NiO

Occupation matrix control of d- and f-electron localisations using DFT + U

Defect calculations in semiconductors through a dielectric-dependent hybrid DFT functional: The case of oxygen vacancies in metal oxides

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