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.

scholarly journals INVESTIGATION OF NEW POLYMORPHIC VARIETIES OF BORON NITRIDE WITH DIAMOND-LIKE STRUCTURES

2020 ◽  
pp. 493-503
Author(s):  
Дмитрий Сергеевич Ряшенцев ◽  
Евгений Анатольевич Беленков
Keyword(s):  
Density Functional Theory ◽  
Boron Nitride ◽  
Bulk Density ◽  
Density Functional ◽  
Theoretical Study ◽  
Density Functional Theory Method ◽  
Theory Method ◽  
Functional Theory ◽  
Sublimation Energy ◽  
The Density Functional Theory

В работе проведено теоретическое исследование новых полиморфных разновидностей нитрида бора, имеющих алмазоподобные структуры. В результате расчетов методом теории функционала плотности в градиентном приближении была установлена возможность устойчивого существования четырех новых структурных разновидностей нитрида бора: BN - LA4, BN - LA5, BN - LA6 и BN - LA7 . Энергия сублимации новых BN фаз варьируется в диапазоне от 16,85 до 17,84 эВ/(BN), ширина запрещенной зоны - от 4,34 до 6,07 эВ. Объемная плотность BN полиморфов изменяется от 3,020 до 3,452 г/см. The article presents a theoretical study of new polymorphic varieties of boron nitride with diamond-like structures. As a result of calculations by the density functional theory method in the gradient approximation, the possibility of stable existence of four new structural varieties of boron nitride: BN - LA4, BN - LA5 , BN - LA6, and BN - LA7 was established. The sublimation energy of new BN phases varies in the range from 16,85 to 17,84 eV/(BN), the band gap is from 4,34 to 6,07 eV. The bulk density of BN polymorphs varies from 3,020 to 3,452 g/cm.

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.

Study of the Stability and Chemical Reactivity of a Series of Tetrazole Pyrimidine Hybrids by the Density Functional Theory Method (DFT)

2021 ◽  
Vol 37 (4) ◽  
pp. 805-812
Author(s):  
Ahissandonatien Ehouman ◽  
Adjoumanirodrigue Kouakou ◽  
Fatogoma Diarrassouba ◽  
Hakim Abdel Aziz Ouattara ◽  
Paulin Marius Niamien
Keyword(s):  
Density Functional ◽  
Theoretical Study ◽  
Molecular Descriptors ◽  
Chemical Reactivity ◽  
Density Functional Theory Method ◽  
Functional Theory ◽  
Reactivity Descriptors ◽  
The Density Functional Theory ◽  
The Stability ◽  
Global Reactivity Descriptors

Our theoretical study of stability and reactivity was carried out on six (06) molecules of a series of pyrimidine tetrazole hybrids (PTH) substituted with H, F, Cl, Br, OCH3 and CH3 atoms and groups of atoms using the density function theory (DFT). Analysis of the thermodynamic formation quantities confirmed the formation and existence of the series of molecules studied. Quantum chemical calculations at the B3LYP / 6-311G (d, p) level of theory determined molecular descriptors. Global reactivity descriptors were also determined and analyzed. Thus, the results showed that the compound PTH_1 is the most stable, and PTH_5 is the most reactive and nucleophilic. Similarly, the compound PTH_4 is the most electrophilic. The analysis of the local descriptors and the boundary molecular orbitals allowed us to identify the preferred atoms for electrophilic and nucleophilic attacks.

Hydrogen-Bonded Interactions in the Systems L-Cysteine - H2SeO3 and L-Cysteine -H2SeO4

2013 ◽  
pp. 169-179
Author(s):  
Alexei N. Pankratov ◽  
Nikolay A. Bychkov ◽  
Olga M. Tsivileva
Keyword(s):  
Density Functional ◽  
Density Functional Theory Method ◽  
Thiol Group ◽  
Mutual Orientation ◽  
Theory Method ◽  
Functional Theory ◽  
Compound A ◽  
The Density Functional Theory ◽  
The Enthalpy Of Formation ◽  
Hydrogen Bonded

Using the density functional theory method at the B3LYP/6-31G(d,p) level of theory, the formation of hydrogen-bonded complexes of L-cysteine with selenious and selenic acids has been studied. In both cases of selenium-containing acids, the complexes occur preferably by cysteine carboxylic group, therewith the enthalpy of formation values consist from –19 to –21 kcal/mol, and free energy from –6 to –9 kcal/mol. Probably, the initial act of interaction in the system hydroxyl-containing selenium compound - a-amino acid, proceeding with mutual orientation of the reactants molecules and intermolecular hydrogen bonds formation, serves as a prerequisite for the thiol group capability of participating in the subsequent stages (including more completed transformations) of biologically important reactions.

Computational insights into the photophysical and electroluminescence properties of homoleptic fac-Ir(C^N)3 complexes employing different phenyl-derivative-featuring phenylimidazole-based ligands for promising phosphors in OLEDs

2016 ◽  
Vol 45 (7) ◽  
pp. 3034-3047 ◽  
Author(s):  
Jieqiong Li ◽  
Li Wang ◽  
Kenan Sun ◽  
Jinglai Zhang
Keyword(s):  
Density Functional Theory ◽  
Electronic Structures ◽  
Density Functional ◽  
Photophysical Properties ◽  
Density Functional Theory Method ◽  
Theory Method ◽  
Functional Theory ◽  
Phenyl Derivative ◽  
The Density Functional Theory

The electronic structures and photophysical properties of three homoleptic iridium(iii) complexes IrL3 with C^N ligands are investigated by means of the density functional theory method.

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