Materials simulations using VASP—a quantum perspective to materials science

Häfner, J.

doi:10.1016/j.cpc.2007.02.045

Cited by 290 publications

(120 citation statements)

References 67 publications

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“…La Teoría de la Funcional Densidad (DFT) [23,24] se usa a a través de la implementación en el Viena AbInitio Simulation Package (VASP) [33,34]. Las Interacciones ión-electrón se tratan mediante el método de las ondas planas aumentadas (PAW) [35].…”

Section: Métodosunclassified

Esfuerzo de corte en Interfaces Fe/Fe3O4

et al. 2018

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RESUMENLa estabilidad mecánica de los óxidos formados sobre las aleaciones de uso industrial, y su adhesión al sustrato metálico es de vital importancia para determinar la susceptibilidad de las aleaciones a los medios en contacto y la aplicabilidad en condiciones de alta temperatura u otras condiciones extremas. En este contexto, la energía de adhesión es uno de los parámetros principales a determinar. Los métodos atomísticos como la Teoría del Funcional de la Densidad (DFT) se presentan como una herramienta fundamental para calcular este parámetro en interfases Oxido/Metal. En este trabajo se estudia con esta técnica la interfaz Fe(BCC)/Magnetita. El interés en este sistema radica en que se ha visto que la magnetita (Fe 3 O 4 ) es el óxido en contacto con el metal en condiciones de corrosión generalizada, e incluso las capas de óxido pasivante pueden tener cierta similitud con esta desde el punto de vista estructural. Dado que la magnetita es una espinela inversa de estructura cristalina y el hierro posee una estructura BCC, se modela la interfaz Fe3O4[001]-Fe[001] teniendo en cuenta que experimentalmente se observa la relación de orientaciones Fe3O4[100]||Fe[110] para la misma. A lo largo de la dirección [001] en el óxido se alternan los planos de composición FeO 2 y Fe, aunque aquí solo se trata la terminación Fe de la magnetita, ya que se ha demostrado que forma la interfaz más estable [1,2]. Se utiliza DFT para calcular el trabajo necesario para deslizar las superficies en relación a las direcciones principales de la interfaz, para luego calcular el potencial interfacial en función de las coordenadas generalizadas de la misma según el modelo de WEI y HUTCHINSON [3]. Este potencial puede ser utilizado en modelos de meso escala de la interfaz, por ejemplo para el cálculo de la tenacidad de la misma.Palabras clave: Adhesión Interfacial, Potencial Interfacial, Magnetita, DFT. ABSTRACTThe mechanical stability of oxides formed on metallic alloys is a key concern in the determination of component susceptibility to the medium in contact and the applicability of the alloy to high temperatures and other extreme conditions. In this context, the energy of adhesion is a key parameter. Density functional Theory (DFT) and other atomistic methods are fundamental tools in the determination of this quantity for Metal/Oxide interfaces. In this paper Fe(BCC) / Magnetite interface is assessed within the DFT approach. This system is of general interest, given that magnetite (Fe 3 O 4 ) is the oxide in direct contact with the metal under generalized corrosion and for a wide range of conditions. Moreover, it has been demonstrated that passive films on iron alloys exhibit similar structural properties. Magnetite is an inverse spinel with structure, while Iron has a BCC crystal structure. [110]. In the (001) direction, atomic layers with compositions FeO 2 and Fe are alternated. Here only the Fe termination is treated, as it has been proved that it constitutes the most stable interface [1,2]. DFT is used to calculate the work need...

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Section: Métodosunclassified

Esfuerzo de corte en Interfaces Fe/Fe3O4

et al. 2018

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“…More information on the method and its application in material science can be obtained e.g. from [21]. The energy cutoff controlling the accuracy of the calculation was set to 500 eV representing an extended basis set and consequently highly accurate calculations.…”

Section: Experimental and Calculationsmentioning

confidence: 99%

High temperature powder diffraction and solid state DFT study of β‐cryolite (Na₃AlF₆)

Smrčok¹,

Kucharík

Tovar

et al. 2009

Cryst. Res. Technol.

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Neutron and synchrotron powder diffraction data for β-cryolite were collected within 550-800(880) °C. Atomic coordinates of Al, F and Na atoms were obtained by both neutron Rietveld refinement and energy minimization in solid state at DFT level of theory. It was shown that although Rietveld refinements with fluorine atoms statically displaced from the 24e to the 96k special position of the Fm-3m space group provide a reasonable fit to the experimental data, the refined structure differ from that obtained by the total energy minimization. The structure with the minimum of the total energy corresponds to the low temperature α-phase with a zigzag arrangement of the polyhedra built around the Al and Na atoms.

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“…The first principle calculations were performed within the GGA method [13] according to DFT using VASP code [14][15][16][17][18][19][20][21]. Interactions of the ions and electrons with each other's was characterized by PAW method [22].…”

Section: Methodsmentioning

confidence: 99%

Ab-<i>initio</i> Calculations of the Physical Properties in Gallium Nitride at Equilibrium Phases: Rocksalt and Wurtzite

Soykan

2017

SDÜ Fen Bil Enst Der

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Ab-initio total energy calculations have been performed utilizing the Density Functional Theory (DFT) inside the generalized gradient approximation (GGA) parameterized by Perdew-Burke-Ernzerhof (PBE). Interactions of the ions and electrons with each other's was characterized via PAW potential within the valance electron configurations Ga-4s 2 4p 1 and N-2p 2 2p 3 to investigate the physical properties in the rocksalt B1 and wurtzite B4 phases. The equilibrium transition pressure (Pt) from B4 to B1 was estimated at about 33.66 GPa by using the common tangent construction. The DFT calculations indicate that the upper bands of wurtzite B4 between -0.256 eV and the Fermi level were mostly owing to N-p states. The lowest conduction bands were consisted of a mixture of N-s and Ga-s states. The valance band maximum and the conduction band minimum occured at the Γ symmetry point. Concordantly, B4 phase of GaN had a direct band gap at Γ-point, which calculated as 1.702 eV. The highest valance band of rocksalt B1 were consisted of with a major contribution of N-2p states. Although, the indirect band gap of the rocksalt B1 phase has been reported from the valance band maximum at the L-point to the conduction band minimum along the X direction [7], we observed the indirect energy band gap from the valance band maximum at the L-point to the conduction band minimum along the Γ direction. Our calculated value of indirect energy band gap for the rocksalt B1 phase was 0.777 eV and it was lower than the previous calculations. GPa olarak hesaplanmıştır. DFT hesapları wurtzite B4'ün en üst bandlarının -0.256 eV ile Fermi seviyesi arasında çoğunlukla N-p durumlarına bağlı olduğunu ortaya koymaktadır. En düşük iletim bandı N-s ve Ga-s durumlarının bir karışımından oluşmaktadır. Valans bandının maksimumu ve iletim bandının minimumu Γ simetri noktasında meydana gelmektedir. Buna paralel olarak, GaN'ün B4 fazı Γ noktasında 1.702 eV olarak hesaplanan bir dolaysız (direkt) band aralığına sahiptir. Rocksalt B1 fazının en yüksek valans bandı başlıca N-2p durumlarının katkılarından oluşmaktadır. Rocksalt B1 fazının dolaylı (in direkt) band aralığının valans bandının en üst bölgesi L-noktasından iletim bandının en alt bölgesi X yönünde olduğu rapor edilmesine rağmen [7], biz dolaylı (in direkt) band aralığını valans bandının en üst bölgesi L noktasından iletim bandının en alt bölgesi Γ yönünde olduğunun gözlemledik. Rocksalt B1 fazı için bizim hesapladığımız dolaylı (in direkt) band aralığı değeri 0.777 eV'dir ve önceki çalışmalardan daha düşüktür. Galyum

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Materials simulations using VASP—a quantum perspective to materials science

Cited by 290 publications

References 67 publications

Esfuerzo de corte en Interfaces Fe/Fe3O4

Esfuerzo de corte en Interfaces Fe/Fe3O4

High temperature powder diffraction and solid state DFT study of β‐cryolite (Na₃AlF₆)

Ab-<i>initio</i> Calculations of the Physical Properties in Gallium Nitride at Equilibrium Phases: Rocksalt and Wurtzite

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Materials simulations using VASP—a quantum perspective to materials science

Cited by 290 publications

References 67 publications

Esfuerzo de corte en Interfaces Fe/Fe3O4

Esfuerzo de corte en Interfaces Fe/Fe3O4

High temperature powder diffraction and solid state DFT study of β‐cryolite (Na3AlF6)

Ab-<i>initio</i> Calculations of the Physical Properties in Gallium Nitride at Equilibrium Phases: Rocksalt and Wurtzite

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High temperature powder diffraction and solid state DFT study of β‐cryolite (Na₃AlF₆)