scholarly journals AB INITIO CALCULATIONS OF THE CRYSTALLINE AND ELECTRONIC STRUCTURE OF 5-7 FLUOROGRAPHENE VARIETIES

2020 ◽  
pp. 326-337
Author(s):  
Максим Евгеньевич Беленков ◽  
Владимир Михайлович Чернов
Keyword(s):  
Density Functional ◽  
Density Functional Theory Method ◽  
Band Gaps ◽  
First Principle ◽  
Functional Theory ◽  
Graphene Layers ◽  
First Principle Calculations ◽  
Deformation Parameters ◽  
The Density Functional Theory ◽  
Structural And Electronic Properties

Первопринципные расчеты структуры и электронных свойств двух новых полиморфных разновидностей фторографена были выполнены методом теории функционала плотности. Новые слои фторографена могут формироваться при химической адсорбции фтора на поверхности 5 - 7 графеновых слоев. Структура слоя первого типа более деформирована по сравнению со структурой второго типа (деформационные параметры Def = 60,48° и Def = 31,51° ). Энергии сублимации и ширины запрещенных зон составляют 13,85, 14,17 эВ/(CF), и 4,09, 3,32 эВ для CF - L слоев T1, T2 типов соответственно. First-principle calculations of the structural and electronic properties of two new polymorphic varieties of fluorographene were performed using the density functional theory method. New layers of fluorographene can be formed during chemical adsorption of fluorine on the surface of 5 - 7 graphene layers. The structure of the layer of the first type is more deformed in comparison with the structure of the second type (deformation parameters Def = 60,48 ° and Def = 31,51 °). Sublimation energies and band gaps are 13,85, 14,17 eV/(CF), and 4,09, 3,32 eV for CF-L layers of T1, T 2 types, respectively.

First-Principle Study of Structural and Electronic Properties of Ti-Doped SnO2

2013 ◽  
Vol 634-638 ◽  
pp. 2545-2549 ◽  
Author(s):  
Jing Kai Yang ◽  
Hong Li Zhao ◽  
Yan Zhu ◽  
Li Ping Zhao ◽  
Jian Li
Keyword(s):  
Electronic Properties ◽  
Density Functional ◽  
First Principle ◽  
Generalized Gradient ◽  
Functional Theory ◽  
First Principle Calculations ◽  
Generalized Gradient Approximation ◽  
The Density Functional Theory ◽  
Structural And Electronic Properties ◽  
Calculation Results

The structural and electronic properties of Ti-doped SnO2with 6.25 at.% are investigated with the first principle calculations based on the density functional theory within the generalized gradient approximation. The calculation results indicate that the crystal structure of Sn0.9375Ti0.0625O2possesses a smaller volume; the bond length of Ti-O is shorter than that of Sn-O; the relative angle θ change value of Sn-O-Sn→Ti-O-Ti is about 1.07%. Ti-O bond possesses more covalent ingredient and stronger bond energy than Sn-O bond. After the replacement of one Ti atom, O atom bonded with Ti atom possessed fewer electrons, the ratio of charges possessed by Ti atom and O atom dose not agree with the stoichiometry of compound, create more holes at the top of VB of Sn0.9375Ti0.0625O2, and lead to the increase of the conductivity.

scholarly journals STRUCTURE AND STABILITY OF A TETRAGONAL DIAMOND-LIKE LAYER: FIRST-PRINCIPLE CALCULATIONS

2020 ◽  
pp. 405-414
Author(s):  
Владимир Андреевич Грешняков ◽  
Евгений Анатольевич Беленков
Keyword(s):  
Surface Density ◽  
Density Functional ◽  
Theoretical Study ◽  
Density Functional Theory Method ◽  
First Principle ◽  
Theory Method ◽  
Functional Theory ◽  
First Principle Calculations ◽  
Tetragonal Lattice ◽  
The Density Functional Theory

Методом теории функционала плотности было выполнено теоретическое исследование нового слоевого полиморфа алмаза DL, состоящего из двух полимеризованных тетрагональных графеновых слоев L. Установлено, что новый алмазоподобный слой имеет двумерную тетрагональную решетку с параметром a = b = 0,3822 нм и толщиной 0,1599 нм. Рассчитанные поверхностная плотность и ширина запрещенной зоны этого слоя равны 0,109 мкг/см и 2,63 эВ, соответственно. Новый слой DL должен быть устойчивым, как минимум, до 220 К. Также установлено, что слой DL может быть получен при сильном одноосном сжатии двух графеновых слоев L при давлении 29,6 ГПа. Using the density functional theory method, a theoretical study of a novel layered DL polymorph of diamond, consisting of two polymerized tetragonal graphene L layers, was performed. It was established that the new diamond-like layer has a two-dimensional tetragonal lattice with the parameter a = b = 0,3822 nm and a thickness of 0,1599 nm. The calculated surface density and band gap of this layer are 0,109 μg/cm and 2,63 eV, respectively. The new DL layer must be stable up to at least 220 K. It was also found that the DL layer can be obtained by strong uniaxial compression of two graphene L layers at a pressure of 29,6 GPa.

Ab Initio Calculations of New α-L5-7a and β-L5-7a Graphyne Polymorphic Varieties

2022 ◽  
Vol 1049 ◽  
pp. 180-185
Author(s):  
Viktor Mavrinskii ◽  
Evgeniy A. Belenkov
Keyword(s):  
Density Functional ◽  
Electronic States ◽  
Density Functional Theory Method ◽  
Geometric Optimization ◽  
Initial Structure ◽  
Functional Theory ◽  
Graphene Layers ◽  
Density Of Electronic States ◽  
Sublimation Energy ◽  
The Density Functional Theory

Calculations of the structural and energy parameters, band structure and density of electronic states of new structural varieties of graphyne have been performed by the density functional theory method. The initial structure of the nine polymorphs was theoretically constructed on the basis of the 5-7a graphene layer. As a result of the calculations, the structure of only five graphyne layers was found to be stable: α-L5-7a, β1-L5-7a, β2-L5-7a, β3-L5-7a and β4-L5-7a. The structure of layers γ1-L5-7a, γ2-L5-7a, and γ3-L5-7a is transformed into the structure of graphene layers by geometric optimization, and the graphyne layer γ4-L5-7a is transformed sp+sp2 layer L3-6-13. The sublimation energy of the stable graphyne polymorphs varies from 6.66 to 6.78 eV/atom. The density of electronic states at the Fermi energy level for all α-L5-7a and β-L5-7a layers of graphyne is different from zero, so the new graphyne polymorphs should have metallic properties.

scholarly journals Elastic and optical properties of sillenites: First principle calculations

2020 ◽  
Vol 557 (1) ◽  
pp. 98-104 ◽  
Author(s):  
Husnu Koc ◽  
Selami Palaz ◽  
Sevket Simsek ◽  
Amirullah M. Mamedov ◽  
Ekmel Ozbay
Keyword(s):  
Optical Properties ◽  
Electronic Structures ◽  
Density Functional ◽  
Electronic Band Structure ◽  
First Principle ◽  
Electronic Band ◽  
Functional Theory ◽  
First Principle Calculations ◽  
Optical Functions ◽  
The Density Functional Theory

In the present paper, we have investigated the electronic structure of some sillenites - Bi12MO20 (M = Ti, Ge, and Si) compounds based on the density functional theory. The mechanical and optical properties of Bi12MO20 have also been computed. The second-order elastic constants have been calculated, and the other related quantities have also been estimated in the present work. The band gap trend in Bi12MO20 can be understood from the nature of their electronic structures. The obtained electronic band structure for all Bi12MO20 compounds is semiconductor in nature. Similar to other oxides, there is a pronounced hybridization of electronic states between M-site cations and anions in Bi12MO20. Based on the obtained electronic structures, we further calculate the frequency-dependent dielectric function and other optical functions.

scholarly journals SIMULATION OF POLYMORPHIC VARIETIES OF HEXAGONAL GRAPHENE FUNCTIONALIZED BY HYDROXYL GROUPS

2021 ◽  
pp. 541-551
Author(s):  
Максим Евгеньевич Беленков ◽  
Владимир Михайлович Чернов
Keyword(s):  
Electronic Structure ◽  
Density Functional ◽  
Density Functional Theory Method ◽  
Hydroxyl Groups ◽  
Functional Theory ◽  
Graphene Layers ◽  
Sublimation Energy ◽  
The Density Functional Theory ◽  
Direct Band ◽  
Oxygen Bond

Моделирование кристаллической и электронной структуры слоев гексагонального графена, на поверхность которых были химически адсорбированы гидроксильные группы, было выполнено методом теории функционала плотности. В результате расчетов была установлена возможность устойчивого существования пяти структурных разновидностей COH - L слоев. Слоевая плотность изменяется от 1,62 до 1,72 мг/м. Длина водород-кислородной связи варьируется в диапазоне от 1,046 до 1,079 Å, а углерод-кислородной связи - от 1,455 до 1,465 Å. Ориентация O - H связей относительно плоскости слоев может варьироваться в зависимости от выбора элементарной ячейки слоя. Минимальной энергией сублимации и равной 18,69 эВ/(COH) обладает слой COH-L - T4, а максимальную энергию сублимации 18,93 эВ/(COH) имеет слой COH - L - T1. Электронная структура всех COH слоев характеризуется наличием прямой запрещенной зоны на уровне энергии Ферми, изменяющейся в диапазоне от 3,02 до 4,56 эВ. Computer simulation of the crystal and electronic structure of hexagonal graphene layers, on the surface of which hydroxyl groups, chemically adsorbed, was performed by the density functional theory method. As a result of calculations, the possibility of the stable existence of five structural varieties of COH - L layers was established. The layer density varies from 1,62 to 1,72 mg/m. The length of the hydrogen-oxygen bond varies in the range from 1,046 to 1,079 Å, and the carbon-oxygen bond-from 1,455 to 1,465 Å. The orientation of the -OH bonds relative to the surface of the layers can vary depending on the choice of the unit cell of the layer. Layer COH - L - T4 has the minimum sublimation energy equal to 18,69 eV/(COH), and layer COH - L - T1 has the maximum sublimation energy 18,93 eV/(COH). The electronic structure of all COH layers is characterized by the presence of a direct band gap at the Fermi energy level, varying in the range from 3,02 to 4,56 eV.

scholarly journals Structural and Electronic Properties of Pure Ta, TaNO, and TaZrNO with Ab Initio Calculations

2012 ◽  
Vol 2012 ◽  
pp. 1-7 ◽  
Author(s):  
T. Chihi ◽  
M. Fatmi ◽  
M. Guemmaz ◽  
J. C. Parlebas
Keyword(s):  
Interatomic Distance ◽  
Density Functional ◽  
Electronic Conductivity ◽  
First Principle ◽  
Functional Theory ◽  
First Principle Calculations ◽  
Structural And Electronic Properties ◽  
Densities Of States ◽  
Self Consistent ◽  
The Difference

This paper presents the results of self-consistent first-principle calculations for the crystal structure and electronic structure of pure tantalum, TaNO, and TaZrNO within density functional theory (DFT) for the sake of comparison and shows the influence of allowing elements on the interatomic distance and the Fermi level. The large total densities of states (TDOS) value for TaZrNO implies the highest electronic conductivity. The difference in values is due to the Zr metallic atoms presence in TaZrNO compound. There is a strong interaction between Ta and (N, O) (Ta−N=0.39, Ta−O=0.21) in TaON compound, and Zr presence increases this interaction (Ta−N=1.74, Ta−O=0.30) in TaZrON compound.

scholarly journals New polymorphic varieties of boron nitride with graphene-like structures

2021 ◽  
Vol 13 (3) ◽  
pp. 349-354
Author(s):  
Dmitry S. Ryashnetsev ◽  
◽  
Eugeny A. Belenkov ◽  
Keyword(s):  
Boron Nitride ◽  
Density Functional ◽  
Density Functional Theory Method ◽  
Geometric Optimization ◽  
First Principle ◽  
Generalized Gradient ◽  
Functional Theory ◽  
Generalized Gradient Approximation ◽  
The Density Functional Theory ◽  
Nitride Layers

First-principle calculations of the structure and electronic properties of four new polymorphic varieties of graphene-like boron nitride, the structure of which is similar to the structure of graphene polymorphs, the atoms in which are in the spirit of different structural positions, were performed by the density functional theory method in the generalized gradient approximation. As a result of the studies carried out, the possibility of stable existence of three monoatomic boron nitride layers: BN-L4-6-8a, BN-L4-6-8b and BN-L4-10 has been established. The BN-L4-12 layer is transformed into the BN-L4-6-8 layer during geometric optimization. The lengths of interatomic bonds in boron nitride monolayers vary in the range 1.4353 Å ÷ 1.4864 Å, and the bond angles in the range 84.05° ÷ 152.26°. The band gap of the BN layers varies from 3.16 eV to 3.90 eV. Sublimation energies are in the range from 16.67 eV/(BN) to 17.61 eV/(BN).

Atomic and Electronic Structures of Au/TiO2 Catalyst – First-Principle Calculations –

2002 ◽  
Vol 738 ◽  
Author(s):  
Kazuyuki Okazaki ◽  
Yoshitada Morikawa ◽  
Shingo Tanaka ◽  
Satoshi Ichikawa ◽  
Koji Tanaka ◽  
...  
Keyword(s):  
Electronic Structures ◽  
Density Functional ◽  
Titanium Atom ◽  
First Principle ◽  
Hollow Site ◽  
Functional Theory ◽  
Surface Conditions ◽  
First Principle Calculations ◽  
The Density Functional Theory ◽  
Oxygen Atoms

ABSTRACTThe atomic and electronic structures of Au/TiO2(110) systems have been theoretically investigated based on the density functional theory. We have examined Au adsorption on the stoichiometric TiO2(110) surface and on the Ti-rich surface formed by the removal of bridging-oxygen atoms (VOB surface) and the O-rich surface formed by the removal of 6-fold titanium and bridging-oxygen atoms (VTi6OB surface). For the stoichiometric surface, the stable site for the Au adatom is the hollow site of one bridging-oxygen and two in-plane oxygen atoms or the on-top site above 5-fold titanium atom. For the Ti-rich VOB surface, the bridging site of 6-fold titanium atoms along [001] direction is the most stable. In addition, the vacant site of 6-fold titanium atom is the most stable for the O-rich VTi6OB surface. The adhesive energies between the Au adlayer and the TiO2 surface are larger for the non-stoichiometric surfaces than that for the stoichiometric surface. The charge transfer between the Au adatom and the substrate is small for stoichiometric surface. For the Ti-rich VOB surface, the electron transfer occurs from the 6-fold Ti to the Au, while from the Au to the in-plane oxygen for the O-rich VTi6OB surface. It can be said that the TiO2 surface conditions such as defects or non-stoichiometry strongly affect the adsorption energy and electron structure of the Au adsorbed system. This point should be closely related the catalytic property of the Au/TiO2 system.

Structure and Properties of Diamond-Like Phases

2016 ◽  
Vol 845 ◽  
pp. 231-234 ◽  
Author(s):  
Vladimir Greshnyakov ◽  
Evgeniy A. Belenkov
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Structural Parameters ◽  
Three Dimensional ◽  
Density Functional Theory Method ◽  
Theory Method ◽  
Structure And Properties ◽  
Functional Theory ◽  
Graphene Layers ◽  
The Density Functional Theory

The geometrically optimized structures of twenty three carbon diamond-like phases obtained by linking graphene layers, carbon nanotubes, and three-dimensional graphites has been calculated using the density functional theory method and the structural parameters, densities, sublimation energies, electronic properties, and bulk moduli have been calculated.

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