scholarly journals Магнитные, электронные и оптические свойства тетраборатов NiB-=SUB=-4-=/SUB=-O-=SUB=-7-=/SUB=- и CoB-=SUB=-4-=/SUB=-O-=SUB=-7-=/SUB=- в трех структурных модификациях

2021 ◽  
Vol 63 (3) ◽  
pp. 376
Author(s):  
А.С. Шинкоренко ◽  
В.И. Зиненко ◽  
М.С. Павловский
Keyword(s):  
Software Package ◽  
Density Functional ◽  
Symmetry Groups ◽  
Magnetic Exchange ◽  
Functional Theory ◽  
Structural Modifications ◽  
The Density Functional Theory ◽  
Densities Of States ◽  
Exchange Constants ◽  
Space Symmetry

Within a framework of the density functional theory using the VASP software package, physical properties of tetraborate compounds NiB4O7 and CoB4O7 in three structural modifications with space symmetry groups of Pbca, Cmcm and P6522 were calculated. The dependences of the enthalpy of compounds on pressure in studied structural modifications are calculated. The calculated electron densities of states and band structures showed that studied compounds in all considered modifications are dielectrics with a band gap of 3-4 eV. The calculation of the magnetic exchange constants was carried out in the Heisenberg model, which showed qualitative agreement with experiment.

scholarly journals Interaction of sulfur with impurities in bcc iron

2021 ◽  
Vol 2103 (1) ◽  
pp. 012071
Author(s):  
A V Verkhovykh ◽  
A A Mirzoev ◽  
Yu K Okishev ◽  
N S Dyuryagina
Keyword(s):  
Density Functional Theory ◽  
Software Package ◽  
Density Functional ◽  
Functional Theory ◽  
The Third ◽  
Bcc Iron ◽  
The Density Functional Theory ◽  
Coordination Spheres ◽  
Strong Repulsion ◽  
Substitutional Impurities

Abstract In this work, the modeling of the sulfur interaction with substitutional impurities (Mn, P) and interstitial (C) has been carried out. All calculations were performed using the density functional theory in the WIEN2k software package. For the first two coordination spheres, there is a strong repulsion between carbon and sulfur, but in the third relative position, a slight attraction arises between the atoms. When sulfur interacts with manganese, attraction occurs only for the first coordination sphere, while the dissolution energy of both manganese and sulfur decreases. In the case of the S-P interaction, the binding energy is negative, and the dissolution energy of both sulfur and phosphorus decreases for all configurations, although the distance between phosphorus and sulfur increases. It can be assumed that the presence of phosphorus leads to the accumulation of sulfur in the material.

Structures and Electronic Properties of Graphyne Layers

2016 ◽  
Vol 845 ◽  
pp. 239-242 ◽  
Author(s):  
Tatyana Belenkova ◽  
Vladimir Chernov ◽  
Viktor Mavrinskii
Keyword(s):  
Electronic Properties ◽  
Density Functional ◽  
Layered Compounds ◽  
Mixed Structure ◽  
Generalized Gradient ◽  
Functional Theory ◽  
Energy Characteristics ◽  
Structural Modifications ◽  
The Density Functional Theory ◽  
Basic Layer

Theoretical scheme is proposed for obtaining layered compounds consisting of carbon atoms in the sp-and sp2-hybridized states. This scheme is used to find the possibility of existing the seven basic structural modifications of graphyne: α-, β1-, β2-, β3-, γ1-, γ2-, and γ3-graphyne. The basic structural modifications of graphyne contain diatomic polyyne chains and consist only of carbon atoms in two different crystallographically equivalent states. Other nonbasic structural modifications of graphyne can be formed via the elongation of the carbyne chains and via the formation of graphyne layers with a mixed structure consisting of basic layer fragments. The geometrical optimization of the structure and the calculation of energy characteristics and electronic properties of graphyne layers were performed using ab initio calculations based on the density functional theory in the generalized gradient approximation. The energy of sublimation is found to be maximal for γ graphynes, which should be the most stable structural modifications of graphyne.

scholarly journals Термодинамическая стабильность твердых растворов In-=SUB=-x-=/SUB=-Ga-=SUB=-1-x-=/SUB=-N

2021 ◽  
Vol 47 (19) ◽  
pp. 51
Author(s):  
С.А. Кукушкин ◽  
А.В. Осипов
Keyword(s):  
Density Functional ◽  
Room Temperature ◽  
Epitaxial Films ◽  
Hexagonal Structure ◽  
Symmetry Groups ◽  
Functional Theory ◽  
Thermodynamic Potentials ◽  
The Density Functional Theory ◽  
The Stability ◽  
Group Theoretical Analysis

A group-theoretical analysis of solid solutions of indium and gallium nitrides InxGa1-xN was carried out, and all the main symmetry groups were found for these solutions with the initial hexagonal structure. The thermodynamic potentials of the main phases with different compositions x are calculated using the density functional theory. It is shown that for small and large x, i.e. at 0 <x <0.2 and 0.8 <x <1, there is a large number of monoclinic phases Pm and P2_1, which are stable with respect to decomposition into InN and GaN at room temperature. In the range 0.2 <x <0.8, there are only two stable orthorhombic phases Cmc2_1 with compositions x = 1/3 and x = 2/3. All basic geometric and thermodynamic properties of various InxGa1-xN phases have been calculated. It was found that the stability of InxGa1-xN epitaxial films increases with growth on InN and decreases with growth on GaN.

First-Principles Study of the ZnO(1120) Structure and Ti Adsorption

2013 ◽  
Vol 833 ◽  
pp. 70-74
Author(s):  
Zhong Liang ◽  
Guo You Gan ◽  
Jian Hong Yi ◽  
Ji Kang Yan ◽  
Jing Hong Du ◽  
...  
Keyword(s):  
First Principles ◽  
Density Functional ◽  
Negative Charge ◽  
Geometrical Structure ◽  
Covalent Bond ◽  
Outer Electron ◽  
Functional Theory ◽  
The Density Functional Theory ◽  
Densities Of States ◽  
Negative Charge Density

Based on the density functional theory, this paper calculated the geometrical and electronic structural properties of ZnO(11¯20) surfaces and analyzed ZnO(11¯20) surfaces in the structural relaxation, electron density difference, densities of states and the Ti adsorption by using the first-principles and pseudopotential method. According to the computing result, ZnO(11¯20) surfaces are similar in geometrical structure and bulk; at the same time, when Ti adsorbs ZnO(11¯20) surfaces, the negative charge density is special high in the central region between Ti and O, and Ti-O shows obviously better performance than Zn-O in covalent bond, for the reason that the number of outer electron transferred from Ti to O is extremely limited, and the area of negative charge of the surface is large, which can lead to metallic characteristics on the surface

scholarly journals Электронная структура, оптические свойства и поведение под давлением в соединениях CdB-=SUB=-4-=/SUB=-O-=SUB=-7-=/SUB=- и HgB-=SUB=-4-=/SUB=-O-=SUB=-7-=/SUB=-

2018 ◽  
Vol 60 (9) ◽  
pp. 1662
Author(s):  
А.С. Шинкоренко ◽  
В.И. Зиненко ◽  
М.С. Павловский
Keyword(s):  
Phase Transition ◽  
Density Functional Theory ◽  
Optical Properties ◽  
Band Structure ◽  
Density Functional ◽  
Electronic Band Structure ◽  
Electronic Band ◽  
Functional Theory ◽  
Structural Modifications ◽  
The Density Functional Theory

AbstractAb initio calculations of the structural, electronic, and optical properties of the CdB_4O_7 and HgB_4O_7 tetraborate compounds in three structural modifications with the Pbca , Cmcm , and Pmn 2_1 symmetry have been performed in the framework of the density functional theory using the VASP package. The calculations of the electronic band structure showed that these compounds in all the investigated modifications are dielectrics with a band gap of 2–4 eV. The calculation of the structural properties of the tetraborates under pressure showed that the phase transition between the Pbca and Pmn 2_1 structures in cadmium and mercury tetraborates occurs under pressures of 4.8 and 4.7 GPa, respectively.

scholarly journals Электронная структура кристаллов Be-IV-P-=SUB=-2-=/SUB=- с решеткой халькопирита

2020 ◽  
Vol 62 (11) ◽  
pp. 1799
Author(s):  
Ю.М. Басалаев ◽  
А.Б. Гордиенко
Keyword(s):  
Density Functional Theory ◽  
Dielectric Constant ◽  
Density Functional ◽  
Chalcopyrite Structure ◽  
Optical Absorption Spectra ◽  
Functional Theory ◽  
The Density Functional Theory ◽  
Densities Of States ◽  
Valence Electrons ◽  
Effective Charges

A group of crystalline compounds of the type Be-IV-P2, (IV = C, Si, Ge, Sn) with a chalcopyrite structure has been studied using the density functional theory methods. The equilibrium parameters of the crystal lattice, band structures, spectra of total and partial densities of states, maps of the charge distribution of valence electrons, tensors of dielectric constant and effective charges, and optical absorption spectra are calculated and obtained.

Magnetic Properties of Off-Stoichiometric Ni-X-In (X=Mn, Fe and Co) Magnetic Shape Memory Alloys by First-Principles Calculations

2014 ◽  
Vol 783-786 ◽  
pp. 2419-2422
Author(s):  
Jing Bai ◽  
Jean M. Raulot ◽  
Yu Dong Zhang ◽  
Claude Esling ◽  
Xiang Zhao ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Magnetic Properties ◽  
First Principles ◽  
Software Package ◽  
Density Functional ◽  
First Principles Calculations ◽  
Magnetic Shape Memory ◽  
Magnetic Shape Memory Alloys ◽  
Functional Theory ◽  
The Density Functional Theory

The magnetic properties of the off-stoichiometric Ni2XIn (X=Mn, Fe, Co) are systematically investigated by means of the first–principles calculations within the framework of the density functional theory (DFT) using the Vienna ab initio software package (VASP). The magnitude of the variation in the Ni moments is much larger than that of Mn in the defective Ni2XIn. The value of the Ni magnetic moment sensitively depends on the distance between Ni and X.

scholarly journals Strain Investigation on Spin-Dependent Transport Properties of γ-Graphyne Nanoribbon Between Gold Electrodes

2021 ◽  
Vol 16 (1) ◽  
Author(s):  
Yun Li ◽  
Xiaobo Li ◽  
Shidong Zhang ◽  
Liemao Cao ◽  
Fangping Ouyang ◽  
...  
Keyword(s):  
Transport Properties ◽  
High Performance ◽  
Density Functional ◽  
Strain Engineering ◽  
Molecular Junctions ◽  
Spin Splitting ◽  
Functional Theory ◽  
Spin Dependent Transport ◽  
The Density Functional Theory ◽  
Dependent Transport

AbstractStrain engineering has become one of the effective methods to tune the electronic structures of materials, which can be introduced into the molecular junction to induce some unique physical effects. The various γ-graphyne nanoribbons (γ-GYNRs) embedded between gold (Au) electrodes with strain controlling have been designed, involving the calculation of the spin-dependent transport properties by employing the density functional theory. Our calculated results exhibit that the presence of strain has a great effect on transport properties of molecular junctions, which can obviously enhance the coupling between the γ-GYNR and Au electrodes. We find that the current flowing through the strained nanojunction is larger than that of the unstrained one. What is more, the length and strained shape of the γ-GYNR serves as the important factors which affect the transport properties of molecular junctions. Simultaneously, the phenomenon of spin-splitting occurs after introducing strain into nanojunction, implying that strain engineering may be a new means to regulate the electron spin. Our work can provide theoretical basis for designing of high performance graphyne-based devices in the future.

scholarly journals Electron-phonon interaction in In-induced √7 ×√3 structures on Si(111) from first-principles

2021 ◽  
Author(s):  
I. Yu. Sklyadneva ◽  
Rolf Heid ◽  
Pedro Miguel Echenique ◽  
Evgueni Chulkov
Keyword(s):  
Density Functional Theory ◽  
Double Layer ◽  
First Principles ◽  
Linear Response ◽  
Density Functional ◽  
Single Layer ◽  
Phonon Interaction ◽  
Functional Theory ◽  
Electron Phonon Interaction ◽  
The Density Functional Theory

Electron-phonon interaction in the Si(111)-supported rectangular √(7 ) ×√3 phases of In is investigated within the density-functional theory and linear-response. For both single-layer and double-layer √(7 ) ×√3 structures, it...

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