Structural, elastic and vibrational properties of nanocrystalline lutetium gallium garnet under high pressure

2015 ◽  
Vol 17 (14) ◽  
pp. 9454-9464 ◽  
Author(s):  
V. Monteseguro ◽  
P. Rodríguez-Hernández ◽  
H. M. Ortiz ◽  
V. Venkatramu ◽  
F. J. Manjón ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
High Pressure ◽  
Ab Initio ◽  
Density Functional ◽  
Vibrational Properties ◽  
Functional Theory ◽  
The Density Functional Theory

An ab initio study of the structural, elastic and vibrational properties of the lutetium gallium garnet (Lu3Ga5O12) under pressure has been performed in the framework of the density functional theory, up to 95 GPa.

scholarly journals Compression Behavior and Vibrational Properties of New Energetic Material LLM-105 Analyzed Using the Dispersion-Corrected Density Functional Theory

Molecules ◽  
2021 ◽  
Vol 26 (22) ◽  
pp. 6831
Author(s):  
Tianming Li ◽  
Junyu Fan ◽  
Zhuoran Wang ◽  
Hanhan Qi ◽  
Yan Su ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
High Pressure ◽  
Uniaxial Compression ◽  
Density Functional ◽  
Structural Parameters ◽  
Energetic Material ◽  
Structure Stability ◽  
Vibrational Properties ◽  
Detailed Knowledge ◽  
Functional Theory

The 2,6-diamino-3,5-dinitropyrazine-1-oxide (LLM-105) is a newly energetic material with an excellent performance and low sensitivity and has attracted considerable attention. On the basis of the dispersion-corrected density functional theory (DFT-D), the high-pressure responses of vibrational properties, in conjunction with structural properties, are used to understand its intermolecular interactions and anisotropic properties under hydrostatic and uniaxial compressions. At ambient and pressure conditions, the DFT-D scheme could reasonably describe the structural parameters of LLM-105. The hydrogen bond network, resembling a parallelogram shape, links two adjacent molecules and contributes to the structure stability under hydrostatic compression. The anisotropy of LLM-105 is pronounced, especially for Raman spectra under uniaxial compression. Specifically, the red-shifts of modes are obtained for [100] and [010] compressions, which are caused by the pressure-induced enhance of the strength of the hydrogen bonds. Importantly, coupling modes and discontinuous Raman shifts are observed along [010] and [001] compressions, which are related to the intramolecular vibrational redistribution and possible structural transformations under uniaxial compressions. Overall, the detailed knowledge of the high-pressure responses of LLM-105 is established from the atomistic level. Uniaxial compression responses provide useful insights for realistic shock conditions.

Mechanisms of Diffusion and Dissociation of E-Centers in Silicon

2005 ◽  
Vol 237-240 ◽  
pp. 1129-1134
Author(s):  
Mariya G. Ganchenkova ◽  
V.A. Borodin ◽  
Risto M. Nieminen
Keyword(s):  
Density Functional Theory ◽  
Monte Carlo ◽  
Ab Initio Calculations ◽  
Ab Initio ◽  
Density Functional ◽  
Kinetic Monte Carlo ◽  
Binding Energies ◽  
Functional Theory ◽  
The Density Functional Theory ◽  
Charge States

In this paper we discuss possible mechanisms of PV annealing in Si. Our approach includes a combination of density functional theory and lattice kinetic Monte-Carlo (LKMC) simulations. The density functional theory is used to find the binding energies and jump barriers for P-V pair at different separations (from one to three interatomic bonds between complex constituents) and in different charge states. The mobility of the complex is simulated by LKMC with event probabilities calculated based on the energies from ab-initio calculations. .

scholarly journals Superconductivity in Materials under Extreme Conditions: An ab-initio Prediction from Density Functional Theory

2021 ◽  
Author(s):  
Thiti Bovornratanaraks ◽  
Prutthipong Tsuppayakorn-aek
Keyword(s):  
Density Functional Theory ◽  
High Pressure ◽  
Ab Initio ◽  
Crystal Structures ◽  
Density Functional ◽  
Ambient Pressure ◽  
Extreme Conditions ◽  
Functional Theory ◽  
Novel Structure ◽  
And Performance

The relation between thermodynamically stable and electronic structure preparation is one of the fundamental questions in physics, geophysics and chemistry. Since the discovery of the novel structure, this has remained as one of the main questions regarding the very foundation of elemental metals. Needless to say this has also bearings on extreme conditions physics, where again the relation between structure and performance is of direct interest. Crystal structures have been mainly at ambient conditions, i.e. at room temperature and ambient pressure. Nevertheless it was realized early that there is also a fundamental relation between volume and structure, and that this dependence could be most fruitfully studied by means of high pressure experimental techniques. From a theoretical point of view this is an ideal type of experiment, since only the volume is changed, which is a very clean variation of the external conditions. Therefore, at least in principle, the theoretical approach remains the same irrespective of the high pressure loading of the experimental sample. Theoretical modeling is needed to explain the measured data on the pressure volume relationships in crystal structures. Among those physical properties manifested itself under high pressure, superconductivity has emerged as a prominent property affected by pressure. Several candidate structure of materials are explored by ab initio random structure searching (AIRSS). This has been carried out in combination with density functional theory (DFT). The remarkable solution of AIRSS is possible to expect a superconductivity under high pressure. This chapter provide a systematically review of the structural prediction and superconductivity in elemental metals, i.e. lithium, strontium, scandium, arsenic.

scholarly journals Substantial Variations in the Optical Absorption and Reflectivity of Graphene When the Concentrations of Vacancies and Doping with Fluorine, Nitrogen, and Oxygen Change

2021 ◽  
Vol 22 (13) ◽  
pp. 6832
Author(s):  
Ali Fransuani Jiménez-González ◽  
Juan Manuel Ramírez-de-Arellano ◽  
Luis Fernando Magaña
Keyword(s):  
Density Functional Theory ◽  
Optical Absorption ◽  
Band Structure ◽  
Numerical Simulations ◽  
Ab Initio ◽  
Density Functional ◽  
Functional Theory ◽  
The Density Functional Theory ◽  
Density Values

We performed ab initio numerical simulations with the density functional theory to investigate the variations in the band structure, optical absorption, and the reflectivity of vacancy-graphene doped with nitrogen, oxygen, and fluorine for different densities. We considered the density values 0.78%, 1.02%, 1.39%, 2.00%, 3.12%, 5.55%, and 12.5% for the vacancies and doping. In the infrared and visible ranges for all cases, vacancies included, there is a substantial increment in the absorption and reflectivity concerning graphene. The most significant changes are for fluorine and oxygen at a concentration of 12.5%.

scholarly journals DFT analysis of crystal polarity on graphene surface

2021 ◽  
Vol 2015 (1) ◽  
pp. 012105
Author(s):  
Alexander Pavlov ◽  
Alexey Mozharov ◽  
Yury Berdnikov ◽  
Camille Barbier ◽  
Jean-Christophe Harmand ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Ab Initio ◽  
Density Functional ◽  
Optoelectronic Device ◽  
Device Design ◽  
Theory Analysis ◽  
Functional Theory ◽  
Graphene Surface ◽  
Gan Nanowires ◽  
The Density Functional Theory

Abstract We report an ab-initio study of the preferred polarity for wurtzite GaN nanostructures on virtual graphene substrates. By means of the density functional theory analysis we show that N-polar nanostructures on graphene are energetically favorable in comparison to Ga-polar. These finding are in agreement with experimentally observed N-polarity of wurtzite GaN nanowires grown on graphene substrate. We believe that the revealed polarity preference is of importance for piezoelectric and optoelectronic device design.

Does Osmium Carbide Exist? Ab initio Investigation

2006 ◽  
Vol 987 ◽  
Author(s):  
M. Zemzemi ◽  
M. Hebbache ◽  
D. Zivkovic ◽  
L Stuparevic
Keyword(s):  
Mechanical Properties ◽  
Density Functional Theory ◽  
Transition Metals ◽  
Ab Initio ◽  
Density Functional ◽  
Ambient Pressure ◽  
Hexagonal Structure ◽  
Functional Theory ◽  
The Density Functional Theory ◽  
Good Agreement

AbstractTransition metals of the platinum group (Os, Ir, Pt, Ru, Re, Rh) do not form carbides and nitrides at ambient pressure. Osmium carbide seems to have been synthesized at zero pressure by Kempter and Nadler forty six years ago. According to the authors, OsC crystallizes in WC-type structure and has a hardness equal to 2000 kg mm-2. Up to date, no other experimental confirmation is available. We studied the electronic and mechanical properties of this hypothetical carbide using an approach based on the density-functional theory. We found that the work of the above mentioned authors is sound. The calculated lattice parameters are in good agreement with that given by those authors and a rough estimate also showed that the hardness given by them is reasonable. However, we found that the hexagonal structure of osmium carbide is electronically and mechanically unstable.

scholarly journals Size engineering optoelectronic features of C, Si and CSi hybrid diamond-shaped quantum dots

RSC Advances ◽  
2019 ◽  
Vol 9 (49) ◽  
pp. 28609-28617 ◽  
Author(s):  
H. Ouarrad ◽  
F.-Z. Ramadan ◽  
L. B. Drissi
Keyword(s):  
Density Functional Theory ◽  
Quantum Dots ◽  
Ab Initio ◽  
Density Functional ◽  
Optoelectronic Properties ◽  
Many Body ◽  
Functional Theory ◽  
The Density Functional Theory

Based on the density functional theory and many-body ab initio calculations, we investigate the optoelectronic properties of diamond-shaped quantum dots based graphene, silicene and graphene–silicene hybrid.

scholarly journals Ab initio и экспериментальное исследование колебательных свойств кристаллов TlFeS-=SUB=-2-=/SUB=- и TlFeSe-=SUB=-2-=/SUB=-

2021 ◽  
Vol 63 (10) ◽  
pp. 1637
Author(s):  
З.А. Джахангирли ◽  
Р.Г. Велиев ◽  
И.А. Мамедова ◽  
З.И. Бадалова ◽  
Д.А. Мамедов ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Raman Scattering ◽  
Ab Initio ◽  
Density Functional ◽  
Vibrational Properties ◽  
Site Symmetry ◽  
Functional Theory ◽  
Infrared Reflection ◽  
Raman Modes ◽  
Ir Light

The lattice vibrational properties of TlFeS2 and TlFeSe2 crystals have been studied experimentally using Raman scattering (RS) and infrared reflection (IR) light, as well as theoretically using density functional theory (DFT). The complete vibrational representation, based on the analysis of the factor site symmetry, contains 12 active Raman modes and 9 IR active modes. 6 RS active and 3 IR active modes of them for TlFeS2, and 4 RS active and 3 IR active modes for TlFeSe2 were experimentally detected and identified.

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