The object-oriented DFT program library S/PHI/nX

Boeck, Sixten; Freysoldt, Christoph; Dick, A.; Ismer, Lars; Neugebauer, Jörg

doi:10.1016/j.cpc.2010.09.016

Cited by 81 publications

(46 citation statements)

References 25 publications

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“…The pre-processing to generate unique displacements based on symmetry and the post-processing to construct the dynamical matrix and thus the phonon frequencies in reciprocal space are performed employing the S/ PHI/nX code. 37 In terms of computing TBEs and surface energies, a series of supercells with different numbers of layers (perpendicular to the twinning or surface planes) are employed in order to evaluate the spurious interaction between the defect and its images (due to employment of periodic boundary conditions). The computed lattice constants for pure Mg (a = 3.189 Å and c/a = 1.626) and pure yttrium (a = 3.647 Å and c/a = 1.551) are in very good agreement with experimental data (pure Mg, a = 3.209 Å, c/a = 1.624 and pure yttrium, a = 3.648 Å, c/a = 1.571).…”

Section: Computational Detailsmentioning

confidence: 99%

Atomic structures of twin boundaries in hexagonal close-packed metallic crystals with particular focus on Mg

et al. 2017

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We have investigated twin boundaries in double-lattice hexagonal close-packed metallic materials, focusing on their atomic geometry. Combining accurate ab-initio methods and large-scale atomistic simulations we address the following two fundamental questions: (i) What are the possible intrinsic twin boundary structures in hcp crystals? (ii) Are these structures stable against small distortions? In order to help end a decade-long controversy over the experimental observations of the atomic structures of twin boundaries, we have determined the energetics, spectra, and transition mechanisms of the twin boundaries. Our results confirm that the mechanical stability controls structures which are observed.

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Section: Computational Detailsmentioning

confidence: 99%

Atomic structures of twin boundaries in hexagonal close-packed metallic crystals with particular focus on Mg

et al. 2017

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“…The present study reveals that this is not the case. Analyzing the calculations, we show that the observed attraction is a consequence of a hitherto unknown interaction mechanism-an electrostatic attraction caused by the lateral charge redistribution in the electron spill-out region of metals.To investigate the low coverage adsorption behavior of N, O, F, and Cl on the (0001) surface of hcp Mg, we perform density-functional theory (DFT) calculations using the generalized gradient approximation PBE [11] and the SPHINX package [12] with VASP-PAW potentials [13]. …”

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confidence: 99%

“…To investigate the low coverage adsorption behavior of N, O, F, and Cl on the (0001) surface of hcp Mg, we perform density-functional theory (DFT) calculations using the generalized gradient approximation PBE [11] and the SPHINX package [12] with VASP-PAW potentials [13]. A plane wave basis of 476 eV and k-point sampling with a (18 × 18 × 1) Monkhorst-Pack mesh in a (1 × 1) cell ensure binding energies converged to within 10 meV.…”

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confidence: 99%

Negatively Charged Ions on Mg(0001) Surfaces: Appearance and Origin of Attractive Adsorbate-Adsorbate Interactions

et al. 2014

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Adsorption of electronegative elements on a metal surface usually leads to an increase in the work function and decrease in the binding energy as the adsorbate coverage rises. Using density-functional theory calculations, we show that Cl adsorbed on a Mg(0001) surface complies with these expectations, but adsorption of {N,O,F} causes a decrease in the work function and an increase in the binding energy. Analyzing the electronic structure, we show that the presence of a highly polarizable electron spill-out in front of Mg(0001) causes this unusual adsorption behavior and is responsible for the appearance of a hitherto unknown net-attractive lateral electrostatic interaction between same charged adsorbates.

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“…The interfaces were assumed to be abrupt and without any interdiffusion of atomic species. The exact dimensions of each cell volume were for GaN The basal plane pseudomorphic interfaces between AlN and GaN were studied in detail, for both IIIpolarity and N-polarity, by conducting first-principles density functional theory (DFT) calculations using the multiscale library SP/hi/NGX [29]. In the latter the Perdew-Burke-Ernzehof (PBE) [30] generalized gradient approximation (GGA) was used with an energy cut-off equal to 50 Ry and soft Troullier-Martins pseudopotentials [31].…”

Section: Experimental and Theoretical Methodologymentioning

confidence: 99%

Strain accommodation and interfacial structure of AlN interlayers in GaN

Dimitrakopulos

Kalesaki

Komninou³

et al. 2009

Cryst. Res. Technol.

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The strain accommodation mechanisms at AlN interlayers in GaN, grown by radio‐frequency plasma assisted molecular beam epitaxy, are studied using transmission electron microscopy techniques and atomistic modelling. Interlayers of various thicknesses grown within GaN epilayers deposited on both sapphire and silicon substrates have been employed. Interlayers of thickness below 6 nm do not exhibit line defects although local roughness of the upper interlayer interface is observed as a result of the Al adatom kinetics and higher interfacial energy compared to the lower interface. Above 6 nm, introduction of a‐type misfit and threading dislocations constitutes the principal relaxation mechanism. Due to strain partitioning between AlN and GaN, threading dislocations adopt inclined zig‐zag lines thus contributing to the relief of alternating compressive‐tensile elastic strain across the AlN/GaN heterostructure. The observed dislocation configurations are consistent with a model of independent motion by climb or ancillary glide in response to their localized three‐dimensional strain environment. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

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The object-oriented DFT program library S/PHI/nX

Cited by 81 publications

References 25 publications

Atomic structures of twin boundaries in hexagonal close-packed metallic crystals with particular focus on Mg

Atomic structures of twin boundaries in hexagonal close-packed metallic crystals with particular focus on Mg

Negatively Charged Ions on Mg(0001) Surfaces: Appearance and Origin of Attractive Adsorbate-Adsorbate Interactions

Strain accommodation and interfacial structure of AlN interlayers in GaN

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