Персона: Маслов, Михаил Михайлович
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Interaction of dopants and functional groups adsorbed on the carbon fullerenes: Computational study
© 2020 Elsevier B.V.We apply density functional theory to study the effective interaction between dopant atoms (B, N, Si, P) and functional groups (H, F, Cl, OH) on the surface of carbon fullerenes. Both dopant atoms and functional groups strongly interact through the carbon cage even in diametrically opposite positions. Interaction energies distribute in a wide range from 0.1 to 2 eV and non-monotonically depend on fullerene size and distance between dopants or functional groups. Such interaction cannot be described as a simple Coulomb repulsion or sum of dopants binding energies and cage strain energy. We identify some general trends in relative positions of dopants or functional groups in low-energy isomers. Para position of two functional groups is the most feasible for C60 and larger cages. For lower fullerenes, ortho or other spaced positions may be more preferable. The interaction of foreign atoms embedded into the carbon cages is more complicated. The best relative positions intricately depend on the cage size and chemical nature of dopants. As a rule, ortho and para locations are feasible for C60 and larger cages. However, some exceptions are observed. The effect of thermal vibrations on the considered interactions in doped or functionalized fullerenes is negligible in the temperature range from 300 to 1000 K.
Improved lithium-ion batteries and their communication with hydrogen power
Self-contained power supplies and energy storage continue to improve. The criteria that determine their development include efficiency, safety, adaptability, modifiability, and a number of others. In this work, one of the ways to improve the lithium-ion battery by using a new negative electrode is considered. The possibilities of applicability of the improved lithium-ion battery are discussed, its advantages and disadvantages in relation to a hydrogen fuel cell and power sources using hydrogen fuel are considered. The study of the functioning of the new anode, the material of which is a two-layer silicene on a nickel substrate, is carried out at the atomic level. Improvement of the anode characteristics can be achieved by subjecting it to the neutron doping. Li-ion batteries with an improved anode will have higher charging capacity and power, faster charging and improved safety. (c) 2020 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.
Investigation of magnetic ionic liquids for selective and rapid extraction of gallic acid from complex samples using experimental, statistical modeling and density functional theory studies
Thermal Stability and Vibrational Properties of the 6,6,12-Graphyne-Based Isolated Molecules and Two-Dimensional Crystal
We report the geometry, kinetic energy, and some optical properties of the 6,6,12-graphyne-based systems. We obtained the values of their binding energies and structural characteristics such as bond lengths and valence angles. Moreover, using nonorthogonal tight-binding molecular dynamics, we carried out a comparative analysis of the thermal stability of 6,6,12-graphyne-based isolated fragments (oligomer) and two-dimensional crystals constructed on its basis in a wide temperature range from 2500 to 4000 K. We found the temperature dependence of the lifetime for the finite graphyne-based oligomer as well as for the 6,6,12-graphyne crystal using a numerical experiment. From these temperature dependencies, we obtained the activation energies and frequency factors in the Arrhenius equation that determine the thermal stability of the considered systems. The calculated activation energies are fairly high: 1.64 eV for the 6,6,12-graphyne-based oligomer and 2.79 eV for the crystal. It was confirmed that the thermal stability of the 6,6,12-graphyne crystal concedes only to traditional graphene. At the same time, it is more stable than graphene derivatives such as graphane and graphone. In addition, we present data on the Raman and IR spectra of the 6,6,12-graphyne, which will help distinguish it from the other carbon low-dimensional allotropes in the experiment.
Электронные, энергетические и кинетические характеристики низкоразмерных ковалентных структур с нетрадиционной геометрией каркаса и материалов на их основе
All-nitrogen cages and molecular crystals: Topological rules, stability, and pyrolysis paths
© 2020 by the authors. Licensee MDPI, Basel, Switzerland.We combined ab initio molecular dynamics with the intrinsic reaction coordinate in order to investigate the mechanisms of stability and pyrolysis of N4 ÷ N120 fullerene-like nitrogen cages. The stability of the cages was evaluated in terms of the activation barriers and the activation Gibbs energies of their thermal-induced breaking. We found that binding energies, bond lengths, and quantum-mechanical descriptors failed to predict the stability of the cages. However, we derived a simple topological rule that adjacent hexagons on the cage surface resulted in its instability. For this reason, the number of stable nitrogen cages is significantly restricted in comparison with their carbon counterparts. As a rule, smaller clusters are more stable, whereas the earlier proposed large cages collapse at room temperature. The most stable all-nitrogen cages are the N4 and N6 clusters, which can form the van der Waals crystals with densities of 1.23 and 1.36 g/cm3, respectively. The examination of their band structures and densities of electronic states shows that they are both insulators. Their power and sensitivity are not inferior to the modern advanced high-energy nanosystems.
ПРОГРАММНОЕ ОБЕСПЕЧЕНИЕ ДЛЯ ОПРЕДЕЛЕНИЯ ОПТИМАЛЬНОГО РАЗМЕРА СВЕРХЪЯЧЕЕК ПРИ МОДЕЛИРОВАНИИ КОМПОЗИТНЫХ НАНОМАТЕРИАЛОВ
Программа предназначена для определения оптимального числа элементарных ячеек, составляющих сверхъячейки различных квазидвумерных материалов, для достижения их наибольшей соизмеримости при моделировании композитных низкоразмерных структур. Область применения: компьютерное моделирование квазидвумерных композитных наноматериалов с использованием сверхъячеек. Программа позволяет по заданным постоянным решетки двух различных квазидвумерных материалов получить эффективные размеры их сверхъячеек, обладающие минимальным расхождением структурных параметров. Программа создана при поддержке Министерства науки и высшего образования Российской Федерации от 31.12.2022 № FSWU-2023-0075. Тип ЭВМ: IBM PC-совмест. ПК. ОС: Windows 7/8/9/10.
Hypercubane covalent crystals: Insight from density functional theory
Electronic and optical characteristics of graphene on the molybdenum ditelluride substrate under the uniform mechanical stress
Silicon rebirth: Ab initio prediction of metallic sp3-hybridized silicon allotropes
© 2019 Elsevier B.V.We report the prediction of metallic quasione-dimensional sp3-hybridized silicon allotropes in the form of prismanes. Silicon prismanes or polysilaprismanes are the silicon nanotubes of a special type constructed from the dehydrogenated molecules of cyclosilanes (silicon rings). By means of density functional theory, the electronic, geometry, energy, and some mechanical properties of these tubes are investigated. Our results show that silicon polyprismanes are thermodynamically stable compounds, and the character of the energy spectrum, as well as the behavior of transmission function near the Fermi level, illustrate that they exhibit non-typical for the silicon systems metallic nature. Moreover, the metallic state of polysilaprismanes is resistant to the mechanical stresses applied along their main axis. Unusual properties predicted in the presented study discover new prospects of application of silicon nanostructures as the basic elements of future micro- and nanoelectronics, as well as in energy, metrology, medical, and information technologies.