First principle electronic, structural, elastic, and optical properties of strontium titanate

Ekuma, Chinedu; Jarrell, Mark; Moreno, Juana; Bagayoko, Diola

doi:10.1063/1.3700433

Cited by 47 publications

(47 citation statements)

References 95 publications

(187 reference statements)

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“…These results are in good agreement with other previously reported theoretical studies. 37,38 The oxide interfaces are simulated using supercell geometries with three-dimensional periodic boundary conditions. The supercells are composed of 4.5 unit cells of SRO on top of 6.5 unit cells of STO along [001] direction (see 173705-2 (a STO ¼ 3.905 Å ).…”

Section: Computational Methodology and Interface Modelsmentioning

confidence: 99%

Effect of surface structure on workfunction and Schottky-barrier height in SrRuO3/SrTiO3 (001) heterojunctions

Kumar

Niranjan

2014

Journal of Applied Physics

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We present an ab-initio theoretical study of work functions and surface energies of SrRuO 3 (001) surfaces and Schottky-barrier heights (SBHs) at various interfaces in SrRuO 3 /SrTiO 3 (001) heterostructure within the framework of the density-functional theory. The SrRuO 3 workfunctions are found to exhibit strong dependence on surface terminations. The workfunction of two defect-free SrRuO 3 (001) surface terminations, viz., SrO and RuO 2 , differ by as much as 2.37 eV. The p-type SBH at the RuO 2 /SrO/TiO 2 interface is calculated to be 1.27 eV. The substitution of interfacial SrO layer by isoelectronic BaO layer induces small change in the p-SBH ($0.06 eV). However, the p-SBH is reduced significantly ($0.5 eV) as the RuO 2 layer is substituted by MnO 2 layer due to large change in the interfacial dipole. The p-SBH at different interfaces in SrRuO 3 /SrTiO 3 structures are also estimated using semi-empirical metal-induced-gap-states (MIGS) model. The estimated values are found to be larger by $2 eV than those obtained using ab-initio method, rendering the validity of MIGS model questionable in the prediction of SBH in all-oxide metal/dielectric heterojunctions. The modification of SBH by interfacial doping offers the possibility of contact resistance control in SrRuO 3 /SrTiO 3 heterostructures and related devices. V C 2014 AIP Publishing LLC. [http://dx.

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Section: Computational Methodology and Interface Modelsmentioning

confidence: 99%

Effect of surface structure on workfunction and Schottky-barrier height in SrRuO3/SrTiO3 (001) heterojunctions

Kumar

Niranjan

2014

Journal of Applied Physics

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“…An added motivation stems from the potential applications of the material. Our work portends success in light of the fact that our method, the Bagayoko, Zhao, and Williams (BZW), [18][19][20][21][22] as enhanced by Ekuma and Franklin (BZW-EF), [23][24][25][26][27][28] using LDA and GGA potentials, has not only successfully described numerous semiconductors but also predicted the band gaps of cubic Si 3 N 4 , cubic InN, and rutile TiO 2 , which were later confirmed by the experiment. 24 The rest of this paper is organized as follows: Section II describes the computational method.…”

Section: Introductionmentioning

confidence: 91%

“…Beginning with a small basis set, no smaller than the minimum basis set, the BZW-EF method [23][24][25][26][27]36 requires successive and completely self-consistent calculations with the basis set being augmented in size and changing in angular and radial features. The minimum basis set is the one that is just large enough to account for all the electrons present in the material under study.…”

Section: Methods and Computational Detailsmentioning

confidence: 99%

Calculated electronic, transport, and related properties of zinc blende boron arsenide (zb-BAs)

Nwigboji

Malozovsky

Franklin³

et al. 2016

Journal of Applied Physics

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We present the results from ab-initio, self-consistent density functional theory (DFT) calculations of electronic, transport, and bulk properties of zinc blende boron arsenide. We utilized the local density approximation potential of Ceperley and Alder, as parameterized by Vosko and his group, the linear combination of Gaussian orbitals formalism, and the Bagayoko, Zhao, and Williams (BZW) method, as enhanced by Ekuma and Franklin (BZW-EF), in carrying out our completely self-consistent calculations. With this method, the results of our calculations have the full, physical content of density functional theory (DFT). Our results include electronic energy bands, densities of states, effective masses, and the bulk modulus. Our calculated, indirect band gap of 1.48 eV, from Γ to a conduction band minimum close to X, for the room temperature lattice constant of 4.777 Å, is in an excellent agreement with the experimental value of 1.46 ± 0.02 eV. We thoroughly explain the reasons for the excellent agreement between our findings and corresponding, experimental ones. This work provides a confirmation of the capability of DFT to describe accurately properties of materials, if the computations adhere strictly to the conditions of validity of DFT, as done by the BZW-EF method.

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“…In the original BZW 25,26,30 we added orbitals in the increasing order of the excited energies they represent in the atomic or ionic species. In the BZW-EF method, [27][28][29] for a given principal quantum number and for a given site, we add p, d, and f orbitals, if applicable, before the corresponding s orbital of that quantum number. The realization that the polarization of p, d, and f orbitals has primacy over the spherical symmetry of s orbitals, for the valence electrons in binary molecules and other systems comprising two or more atomic sites, led to this Ekuma and Franklin (EF) enhancement of the method.…”

Section: The Bzw and Bzw-ef Methodsmentioning

confidence: 99%

Understanding density functional theory (DFT) and completing it in practice

2014

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We review some salient points in the derivation of density functional theory (DFT) and of the local density approximation (LDA) of it. We then articulate an understanding of DFT and LDA that seems to be ignored in the literature. We note the well-established failures of many DFT and LDA calculations to reproduce the measured energy gaps of finite systems and band gaps of semiconductors and insulators. We then illustrate significant differences between the results from self consistent calculations using single trial basis sets and those from computations following the Bagayoko, Zhao, and Williams (BZW) method, as enhanced by Ekuma and Franklin (BZW-EF). Unlike the former, the latter calculations verifiably attain the absolute minima of the occupied energies, as required by DFT. These minima are one of the reasons for the agreement between their results and corresponding, experimental ones for the band gap and a host of other properties. Further, we note predictions of DFT BZW-EF calculations that have been confirmed by experiment. Our subsequent description of the BZW-EF method ends with the application of the Rayleigh theorem in the selection, among the several calculations the method requires, of the one whose results have a full, physics content ascribed to DFT. This application of the Rayleigh theorem adds to or completes DFT, in practice, to preserve the physical content of unoccupied, low energy levels. Discussions, including implications of the method, and a short conclusion follow the description of the method. The successive augmentation of the basis set in the BZW-EF method, needed for the application of the Rayleigh theorem, is also necessary in the search for the absolute minima of the occupied energies, in practice. C

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First principle electronic, structural, elastic, and optical properties of strontium titanate

Cited by 47 publications

References 95 publications

Effect of surface structure on workfunction and Schottky-barrier height in SrRuO3/SrTiO3 (001) heterojunctions

Effect of surface structure on workfunction and Schottky-barrier height in SrRuO3/SrTiO3 (001) heterojunctions

Calculated electronic, transport, and related properties of zinc blende boron arsenide (zb-BAs)

Understanding density functional theory (DFT) and completing it in practice

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