Transition levels of defects in ZnO: Total energy and Janak's theorem methods

Chakrabarty, Aurab; Patterson, Charles H.

doi:10.1063/1.4739316

Cited by 23 publications

(30 citation statements)

References 22 publications

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“…Several studies have been reported for ZnO using periodic hybrid density functional calculations which address the electronic structure of the bulk material and/or of the oxygen vacancy related properties. As it also holds for most of the theoretical studies on different materials, those dealing for ZnO can be broadly divided in two families: the ones using all electron methods and a linear combination of atomic orbitals with the orbitals expanded in a basis set of Gaussian type orbitals (GTO), and those describing the inner cores by means of a pseudopotential and expanding the valence electron density in a plane wave (PW) basis set . Gerosa et al presented a comparison of the two approaches for different oxides including ZnO .…”

Section: Introductionmentioning

confidence: 99%

Electronic structure of stoichiometric and reduced ZnO from periodic relativistic all electron hybrid density functional calculations using numeric atom‐centered orbitals

Viñes

2017

J Comput Chem

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The atomic and electronic structure of stoichiometric and reduced ZnO wurtzite has been studied using a periodic relativistic all electron hybrid density functional (PBE0) approach and numeric atom-centered orbital basis set with quality equivalent to aug-cc-pVDZ. To assess the importance of relativistic effects calculations were carried out without and with explicit inclusion of relativistic effects through the zero order regular approximation. The calculated band gap is ~0.2 eV smaller than experiment, close to previous PBE0 results including relativistic calculation through the pseudopotential and ~0.25 eV smaller than equivalent non-relativistic all electron PBE0 calculations indicating possible sources of error in non-relativistic all electron density functional calculations for systems containing elements with relatively high atomic number. The oxygen vacancy formation energy converges rather fast with the supercell size, the predicted value agrees with previously hybrid density functional calculations and analysis of the electronic structure evidences the presence of localized electrons at the vacancy site with a concomitant well localized peak in the density of states ~0.5 eV above the top of the valence band and a significant relaxation of the Zn atoms near to the oxygen vacancy. Finally, present work shows that accurate results can be obtained in systems involving large supercells containing up to ~450 atoms using a numeric atomic centered orbital basis set within a full all electron description including scalar relativistic effects at an affordable cost.

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Section: Introductionmentioning

confidence: 99%

Electronic structure of stoichiometric and reduced ZnO from periodic relativistic all electron hybrid density functional calculations using numeric atom‐centered orbitals

Viñes

2017

J Comput Chem

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“…33 The SJ transition state model is an alternative method to determine CTLs within DFT, which is successfully applied, among others, to wide gap systems. 34,35 This method does not require to compare the total energies of differently charged systems and is therefore less affected from issues arising from the supercell approach. The Kohn-Sham eigenvalues are related to the derivative of the total energy E with respect to the occupation number η i of the respective orbital, 36 …”

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confidence: 99%

Modeling intrinsic defects in LiNbO3 within the Slater-Janak transition state model

Sanna

Schmidt

2014

The Journal of Chemical Physics

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Intrinsic point defects in LiNbO3, i.e., isolated Nb antisites and Li as well Nb vacancies, are investigated from first-principles within the Slater-Janak transition state model. Thereby the electronic structure of the investigated defects is calculated with hybrid exchange-correlation functionals. This approach allows for the calculation of charge transition levels without comparing the total energies of differently charged supercells. The obtained results are in agreement with previous hybrid density-functional theory calculations based on total-energy differences. Li and Nb vacancies can be formed in the V(-)(Li) and V(5-)(Nb) charge states only, as long as the host is not strongly p-type or n-type, respectively. NbLi antisites may capture one or two electrons, forming the defect states often referred to as small bound polaron and bi-polaron.

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“…A variety of approaches have been proposed, 22 including applications of Hubbard-U-like terms (LDA + U or GGA + U) to cation d states 40 or to multiple orbital channels, 41 the Slater-Janak transition model, 42,43 modified pseudopotentials, 44 Becke-Johnson type functionals, 45,46 combining DFT with quasiparticle calculations, 35,36 and hybrid functionals. [47][48][49][50][51][52][53][54][55][56] Hybrid functionals have emerged as the current method of choice, 22 applicable to a wide variety of systems including defects in Si, 47,48 GaAs, 51 diamond, 48 and oxides.…”

Section: Introductionmentioning

confidence: 99%

Computationally predicted energies and properties of defects in GaN

2017

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Recent developments in theoretical techniques have significantly improved the predictive power of density-functional-based calculations. In this review, we discuss how such advancements have enabled improved understanding of native point defects in GaN. We review the methodologies for the calculation of point defects, and discuss how techniques for overcoming the band-gap problem of density functional theory affect native defect calculations. In particular, we examine to what extent calculations performed with semilocal functionals (such as the generalized gradient approximation), combined with correction schemes, can produce accurate results. The properties of vacancy, interstitial, and antisite defects in GaN are described, as well as their interaction with common impurities. We also connect the first-principles results to experimental observations, and discuss how native defects and their complexes impact the performance of nitride devices. Overall, we find that lower-cost functionals, such as the generalized gradient approximation, combined with band-edge correction schemes can produce results that are qualitatively correct. However, important physics may be missed in some important cases, particularly for optical transitions and when carrier localization occurs.

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Transition levels of defects in ZnO: Total energy and Janak's theorem methods

Cited by 23 publications

References 22 publications

Electronic structure of stoichiometric and reduced ZnO from periodic relativistic all electron hybrid density functional calculations using numeric atom‐centered orbitals

Electronic structure of stoichiometric and reduced ZnO from periodic relativistic all electron hybrid density functional calculations using numeric atom‐centered orbitals

Modeling intrinsic defects in LiNbO3 within the Slater-Janak transition state model

Computationally predicted energies and properties of defects in GaN

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