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Гимальдинова, Маргарита Александровна

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Институт нанотехнологий в электронике, спинтронике и фотонике

Институт ИНТЭЛ занимается научной деятельностью и подготовкой специалистов в области исследования физических принципов, проектирования и разработки технологий создания компонентной базы электроники гражданского и специального назначения, а также построения современных приборов на её основе. Наша основная цель – это создание и развитие научно-образовательного центра мирового уровня в области наноструктурных материалов и устройств электроники, спинтроники, фотоники, а также создание эффективной инновационной среды в области СВЧ-электронной и радиационно-стойкой компонентной базы, источников ТГц излучения, ионно-кластерных технологий материалов.

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Гимальдинова

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Маргарита Александровна

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Stabilization of small nitrogen clusters via spatial constraint
(2020) Gimaldinova, M. A.; Zemenkov, L. I.; Merinov, V. A.; Гимальдинова, Маргарита Александровна; Меринов, Валерий Борисович
© 2020 Published under licence by IOP Publishing Ltd.We apply density functional theory to calculate activation barriers for dissociations of small all-nitrogen clusters N4 and N6. The effect of external spatial constraint was also considered. We found that spatial constraint results in significant stabilization of both regarded clusters. So, the spatial constraint can be considered as an efficient method for stabilization of high-energy nitrogen structures.
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Carbon vs silicon polyprismanes: a comparative study of metallic sp(3)-hybridized allotropes
(2020) Maslov, M. M.; Grishakov, K. S.; Gimaldinova, M. A.; Katin, K. P.; Маслов, Михаил Михайлович; Гришаков, Константин Сергеевич; Гимальдинова, Маргарита Александровна; Катин, Константин Петрович
Polyprismanes are the special type of single-walled nanotubes with an extremely small cross-section in the form of a regular polygon. In the presented study, we considered carbon and silicon polyprismanes that are constructed from carbon and silicon five-, six-, seven- and eight-membered rings, respectively. By means of density functional theory using the periodic boundary conditions, the geometry and electronic characteristics of these tubes were investigated. The results obtained indicate that, with an increase in the effective diameter, carbon polyprismanes undergo an abrupt change in electronic properties, which can be described as a transition from the dielectric to the metallic state. The character of the energy spectrum, as well as the behavior of transmission function near the Fermi level, illustrate that at some critical diameter they begin to exhibit non-typical for the sp(3)-carbon systems metallic nature. In such a case, it has been found from the partial density of electronic states calculation that the overlapping of bands near the Fermi level is mainly due to the 2p state of carbon atoms. Unlike carbon analogs, silicon polyprismanes are metals for any considered diameter. The metallic properties of the silicon polyprismanes arise due to the 3p states of the silicon atoms. Unexpected properties endowed by the prismane morphology discover new prospects of application of carbon and silicon nanostructures as the basic elements of future electronics.
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Silicon rebirth: Ab initio prediction of metallic sp3-hybridized silicon allotropes
(2020) Katin, K. P.; Grishakov, K. S.; Gimaldinova, M. A.; Maslov, M. M.; Катин, Константин Петрович; Гришаков, Константин Сергеевич; Гимальдинова, Маргарита Александровна; Маслов, Михаил Михайлович
© 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.
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Kinetic stability of nitrogen cubane inside the fullerene cage: Molecular dynamics study
(2020) Gimaldinova, M. A.; Katin, K. P.; Grishakov, K. S.; Maslov, M. M.; Гимальдинова, Маргарита Александровна; Катин, Константин Петрович; Гришаков, Константин Сергеевич; Маслов, Михаил Михайлович
Using tight-binding molecular dynamics simulations, we study kinetic stability of the nitrogen cubane inside the fullerene carbon cage. The main identified mechanism of N-8 decomposition is the N-N bond breaking with the further rapid "splitting" into the N-2 molecules that can form the strong covalent bonds with the inner surface of the fullerene cage. It is found that the fullerene cage significantly increases the stability of the N-8 cube, but its lifetime at room temperature is insufficient to observe the endohedral complex N-8@C-60 without the use of extreme temperature conditions. It can be synthesized and investigated only at cryogenic temperatures.
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Ab initio modeling of dynamic stability of silicon prismanes
(2020) Gimaldinova, M. A.; Kochaev, A. I.; Maslov, M. M.; Гимальдинова, Маргарита Александровна; Маслов, Михаил Михайлович
We present the results of a study on the dynamic stability of silabiprismanes by means of the density functional theory. Silabiprismanes present an elementary case of a particular type of silicon nanotubes with an extremely small cross-section, constructed from dehydrogenated molecules of cyclosilanes (silicon rings). Unlike higher polysilaprismanes, they are formed by only three silicon rings and described by the chemical formula (Si-n)(3) H-2n. In the presented study, we limited ourselves to the cases n = 5 divided by 7. We focused on a detailed review of the mechanisms of isomerization and decomposition. Configurations of the corresponding transition states were determined, and the kinetic parameters in the Arrhenius law (activation energy and frequency factor) were evaluated. Silabiprismanes are found to be much more stable compounds than their carbon analogous. Their lifetimes at room temperature achieve hundreds of seconds, but at 200 K, their stability increases significantly. Thus, their lifetimes are sufficiently high for the identifying and studying of silicon biprismanes, but not for their industrial applications. Therefore, unsubstituted silabiprismanes require lower temperatures of operation, and their applicability is restricted. Although the general pyrolysis path is the same for all considered cages, its features strongly and non-monotonically depend on n. It is confirmed that the hexagonal and heptagonal silabiprismanes are much more stable than the pentagonal one. We obtained the absence of a direct correlation between the thermodynamic and kinetic stabilities of the silicon cages under consideration.
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The effect of doping on the electronic structure and optical properties of silicon biprismanes: DFT and TD-DFT studies
(2020) Salem, M. A.; Gimaldinova, M. A.; Kochaev, A. I.; Maslov, M. M.; Гимальдинова, Маргарита Александровна; Маслов, Михаил Михайлович
We present the results of a study of three-layered silicon biprismanes doped with methyl radicals and fluorine atoms by means of the density functional theory. Pentagonal, hexagonal, heptagonal, and octagonal doped systems were simulated in this study. We found that larger biprismanes demonstrate weaker interaction with dopants because they are less strained, and their surfaces are "flatter". The weakening of interaction manifests itself by elongation of bond lengths between the silicon cage and the attached radicals. However, the energy gain/loss due to the reaction of substitutional doping is practically independent of the size of the system. The calculated partial Mulliken charges of fluorine atoms are about -0.3 of elementary charges. The corresponding value for methyl radicals is approximately three times smaller. HOMO-LUMO gaps of doped biprismanes demonstrate oscillations with increasing biprismane diameter with a general downward trend. The value of the gaps of the doped biprismanes is in the range from 2 to 3 eV and slightly differs from the gaps of the pristine biprismanes. The optical properties and excited states of doped biprismanes were calculated using the time-dependent density functional theory. Ultra-violet and visible spectra were determined for all considered systems. The absorption frequencies slightly depend on the radical type and the size of the system. However, the presence of radicals results in significant changes in the relative adsorption intensities of biprismanes with different shapes. We found that doping with methyl radicals and fluorine provided prevalent adsorption intensities of octagonal and hexagonal biprismanes, respectively. The observed effect can be used for optical detection of biprismanes with specific shapes or diameters in their mixture with other silicon structures.
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Stability and energy characteristics of extended nitrogen nanotubes: Density functional theory study
(2019) Grishakov, K. S.; Katin, K. P.; Gimaldinova, M. A.; Maslov, M. М.; Гришаков, Константин Сергеевич; Катин, Константин Петрович; Гимальдинова, Маргарита Александровна; Маслов, Михаил Михайлович
© 2019, Institute for Metals Superplasticity Problems of Russian Academy of Sciences. All rights reserved.We apply the density functional theory with B3LYP exchange-correlation energy functional and the basis set 6-31G(d) to investigate structural, energetic, and electronic properties and stability of extended armchair and zigzag nitrogen nanotubes with a length of ≈ 3 nm. The capping effect, as well as the passivation of nanotubes’ ends by hydrogen atoms and hydroxyl groups on their stability, are studied. According to our calculations, pristine nitrogen nanotubes are unstable. Both capping and passivation of the nanotube ends provide thermodynamic stability only for (3, 0) and (4, 0) zigzag nitrogen nanotubes. Moreover, the calculated frequency spectra of considered systems confirm their dynamic stability. We stress the fact that some extended nitrogen nanotubes are found to be stable under ambient conditions, i. e., in the absence of external factors such as pressure, spatial confinement, etc. The calculated HOMO-LUMO gaps for these stable extended systems are of the order of 4 eV, so they can be assigned to the class of insulators. It is shown that nitrogen nanotubes are able to store a large amount of energy and can be used as a basis for new high-energy-density materials. We expect that the all-nitrogen tubes with the longer effective length of similar chiralities are also should be stable.
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Nitro Derivatives of Silaprismanes as High-Energy Compounds: Theoretical Study
(2019) Kochaev, A. I.; Salem, M. A.; Gimaldinova, M. A.; Katin, K. P.; Ryzhuk, R. V.; Kargin, N. I.; Maslov, M. M.; Гимальдинова, Маргарита Александровна; Катин, Константин Петрович; Рыжук, Роман Валериевич; Каргин, Николай Иванович; Маслов, Михаил Михайлович
We present ab initio study of structures and properties of silaprismanes Si2nH2n and their nitro derivatives Si2nH2n-1NO2 (n = 3-10). We found that silaprismane Si10H9NO2 possesses the highest stability among all studied cages. Attached NO2 group results in weak decreasing of the HOMO-LUMO gap. The smaller prismanes bind with NO2 groups more strongly. The comparison between silaprismanes and carbon prismanes is also discussed.
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Ab initio Study of Hydrogen Adsorption on Metal-Decorated Borophene-Graphene Bilayer
(2021) Grishakov, K. S.; Katin, K. P.; Kochaev, A. I.; Kaya, S.; Gimaldinova, M. A.; Maslov, M. M.; Гришаков, Константин Сергеевич; Катин, Константин Петрович; Гимальдинова, Маргарита Александровна; Маслов, Михаил Михайлович
We studied the hydrogen adsorption on the surface of a covalently bonded bilayer borophene-graphene heterostructure decorated with Pt, Ni, Ag, and Cu atoms. Due to its structure, the borophene-graphene bilayer combines borophene activity with the mechanical stability of graphene. Based on the density functional theory calculations, we determined the energies and preferred adsorption sites of these metal atoms on the heterostructure's borophene surface. Since boron atoms in different positions can have different reactivities with respect to metal atoms, we considered seven possible adsorption positions. According to our calculations, all three metals adsorb in the top position above the boron atom and demonstrate catalytic activity. Among the metals considered, copper had the best characteristics. Copper-decorated heterostructure possesses a feasible near-zero overpotential for hydrogen evolution reaction. However, the borophene-graphene bilayer decorated with copper is unstable with respect to compression. Small deformations lead to irreversible structural changes in the system. Thus, compression cannot be used as an effective mechanism for additional potential reduction.
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Energy and Electronic Properties of Nanostructures Based on the CL-20 Framework with the Replacement of the Carbon Atoms by Silicon and Germanium: A Density Functional Theory Study
(2022) Gimaldinova, M. A.; Maslov, M. M.; Katin, K. P.; Гимальдинова, Маргарита Александровна; Маслов, Михаил Михайлович; Катин, Константин Петрович
We consider SinCL-20 and GenCL-20 systems with carbon atoms replaced by silicon/germanium atoms and their dimers. The physicochemical properties of the silicon/germanium analogs of the high-energy molecule CL-20 and its dimers were determined and studied using density functional theory with the B3LYP/6-311G(d,p) level of theory. It was found that the structure and geometry of SinCL-20/GenCL-20 molecules change dramatically with the appearance of Si-/Ge-atoms. The main difference between silicon- or germanium-substituted SinCL-20/GenCL-20 molecules and the pure CL-20 molecule is that the NO2 functional groups make a significant rotation relative to the starting position in the classical molecule, and the effective diameter of the frame of the systems increases with the addition of Si-/Ge-atoms. Thus, the effective framework diameter of a pure CL-20 molecule is 3.208 Г…, while the effective diameter of a fully silicon-substituted Si6CL-20 molecule is 4.125 Г…, and this parameter for a fully germanium-substituted Ge6CL-20 molecule is 4.357 Г…. The addition of silicon/germanium atoms to the system leads to a decrease in the binding energy. In detail, the binding energies for CL-20/Si6CL-20/Ge6CL-20 molecules are 4.026, 3.699, 3.426 eV/atom, respectively. However, it has been established that the framework maintains stability, with an increase in the number of substituting silicon or germanium atoms. In addition, we designed homodesmotic reactions for the CL-20 molecule and its substituted derivatives Si6CL-20/Ge6CL-20, and then determined the strain energy to find out in which case more energy would be released when the framework breaks. Further, we also studied the electronic properties of systems based on CL-20 molecules. It was found that the addition of germanium or silicon atoms instead of carbon leads to a decrease in the size of the HOMO-LUMO gap. Thus, the HOMO-LUMO gaps of the CL-20/Si6CL-20/Ge6CL-20 molecules are 5.693, 5.339, and 5.427 eV, respectively. A similar dependence is also observed for CL-20 dimers. So, in this work, we have described in detail the dependence of the physicochemical parameters of CL-20 molecules and their dimers on the types of atoms upon substitution.