Ionicity and Relaxation Anomalies at III–V Nitride Surfaces

Filippetti, Alessio; Fiorentini, Vincenzo; Cappellini, Giancarlo; Bosin, Andrea

doi:10.1002/(sici)1521-396x(199812)170:2<265::aid-pssa265>3.0.co;2-n

Cited by 16 publications

(15 citation statements)

References 17 publications

(28 reference statements)

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“…However, we found 11,34 that the surface tensile stress actually increases in magnitude by about 20% or 0.3 eV/1×1 area (on average on thex andŷ stress components of the anisotropic reconstructed surface) on Ir (001). Similar results are suggested by experiments 35 for Au (001).…”

Section: Microscopic Analysis Based On the Stress Densitymentioning

confidence: 75%

“…Sometimes an-swering these questions is fundamental to attain a consistent qualitative view of a specific process, and indeed the stress density has been usefully applied in this fashion to the study of surface reconstructions. 10,11 Here, in particular, we discuss briefly the hex reconstruction of Ir (100), an apt example of what we mean by a microscopic analysis performed using stress density.…”

Section: Microscopic Analysis Based On the Stress Densitymentioning

confidence: 99%

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Theory and applications of the stress density

2000

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Drawing on the theory of quantum mechanical stress, we introduce the stress density in density functional theory, and give specific prescriptions for its practical and efficient implementation in the plane wave ultrasoft pseudopotential method within the local-density approximation. In analogy with the Chetty-Martin energy density, the stress density provides a spatial resolution of the contributions to the integrated macroscopic stress tensor. While this resolution is inherently non-unique (gauge-dependent), there exist gauge-independent ways of using it in practice. Here we adopt the following ones: a) calculating integrated macroscopic stresses over appropriately defined parts of a system; b) analyzing macroscopic averages of the stress density; c) analyzing changes in the stress density in response to external perturbation. The abilities of the stress density are demonstrated for a set of representative test cases from surface and interface physics: in perspective, the stress density emerges as vastly more powerful and predictive than the integrated macroscopic stress. 71.15.Mb

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Section: Microscopic Analysis Based On the Stress Densitymentioning

confidence: 75%

Section: Microscopic Analysis Based On the Stress Densitymentioning

confidence: 99%

Theory and applications of the stress density

2000

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“…In fact the calculated stress on clean surfaces of transition and noble metals has so far been found to be tensile. [22][23][24] Ibach has offered an explanation for this tensile stress 21 based on ideas of charge redistribution which cause a contraction of the spacing between the first and the second layers and impact the surface bond lengths. Since not all noble-and transition-metal surfaces display a contraction in the top interlayer spacing, it will be interesting to see if the argument for tensile stress would hold for such surfaces.…”

Section: B Surface Stressmentioning

confidence: 99%

Ab initiocalculations of adsorbate-induced stress on Ni(100)

et al. 2004

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We have calculated the surface stress induced on adsorption of c(2ϫ2) overlayers of O and C using first-principles electronic structure calculations based on density-functional theory within the local-density approximation ͑LDA͒ and nonlocal pseudopotentials. The most remarkable result is found in the case of the C overlayer which introduces a large compressive stress, while that on clean Ni͑100͒ and that in the presence of the O overlayer are found to be tensile and smaller in comparison. We find a correlation between the height of the C overlayer and the resulting clock reconstruction of Ni͑100͒ but no specific relationship between surface stress and surface reconstruction. We discuss our results in the context of experimental data, and insights from electronic structure calculations.

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“…In a subsequent application, the authors were able to solve the difficult case of the hex reconstruction of 5d ͑100͒ surfaces 64 by decoupling the component vertical to the surface from in-plane components in the stress density tensor. Using the same reasoning as Filippetti and Fiorentini use for the hex reconstruction of Pt, 64 we could describe the H-vacancy terminated hydride surface and that of the H/Pd subsurface adsorption system as having a local asymmetric environment. We propose that the stress density is not planar but that it has a three-dimensional vector field related to the asymmetric configurations involved, and this, in turn, correlates to the high absolute values of the strain derivative of the surface energy on both surfaces ͑H-vacancy terminated ␤-PdH͕111͖ and subsurface H/Pd͕111͖͒.…”

Section: A Surface Structure Workfunctions and Surface Stressmentioning

confidence: 99%

The crystalline surfaces of β-PdH{111}: Ideal surface terminations of a stoichiometric bulk compound relevant to heterogeneous catalysis

Jigato

Coussens

King

2003

The Journal of Chemical Physics

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Density functional theory study of water adsorption at reduced and stoichiometric ceria (111) surfacesThe surface chemistry of ␤-PdH͕111͖ is of paramount importance as evidenced by the presence of the binary compound in the bulk of Pd catalytic particles during high pressure hydrogenation processes occuring at the industrial scale. Furthermore, the ͕111͖ plane is the most frequently exposed surface by the catalyst. A systematic study is herein performed which involves the computation of surface structure, workfunction, strain derivative of the surface energy, surface free energy and H binding energy for three surface terminations characterized as H-terminated, Pd-terminated and H-vacancy terminated ␤-PdH͕111͖, by means of a plane-waves pseudopotential electronic structure algorithm. Further results of partial and local density of states, Mulliken charges and local isoelectronic softness complete a full characterization of the physical and chemical properties, which, for the first time are presented for the ␤-PdH͕111͖ surface using the predictive power of density functional theory.

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Ionicity and Relaxation Anomalies at III–V Nitride Surfaces

Cited by 16 publications

References 17 publications

Theory and applications of the stress density

Theory and applications of the stress density

Ab initiocalculations of adsorbate-induced stress on Ni(100)

The crystalline surfaces of β-PdH{111}: Ideal surface terminations of a stoichiometric bulk compound relevant to heterogeneous catalysis

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