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1.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Fedorov A. S., Sadreev A. F.
Заглавие : Thermoactivated transport of molecules H-2 in narrow single-wall carbon nanotubes
Коллективы : RFBR [0602-16132]
Разночтения заглавия :авие SCOPUS: Thermoactivated transport of molecules H 2 in narrow single-wall carbon nanotubes
Место публикации : Eur. Phys. J. B: SPRINGER, 2009. - Vol. 69, Is. 3. - P363-368. - ISSN 1434-6028, DOI 10.1140/epjb/e2009-00152-1
Примечания : Cited References: 40. - We are grateful to S. G. Ovchinnikov for discussions. This work has been supported by RFBR grant 0602-16132.
Предметные рубрики: DIFFUSION
NANOPORES
ENERGY
MOTION
FLUIDS
Ключевые слова (''Своб.индексиров.''): hydrogen molecule--inner potential--lennard-jones potential--periodic potentials--plane wave--potential surfaces--single-wall carbon nanotubes--thermal fluctuations--tube walls--carbon nanotubes--hydrogen--molecules--single-walled carbon nanotubes (swcn)
Аннотация: By use both of the plane wave DFT and the empirical exp-6 Lennard-Jones potential methods we calculate the inner potential in narrow single-wall carbon nanotubes (SWCNT) (6, 0), (7, 0) and (3, 3) which affects the hydrogen molecules. The inner potential forms a goffered potential surface and can be approximated as V(z,r,phi)a parts per thousand V(0)sin (2 pi z/a)+V(r). We show that in these SWCNTs transport of molecules is given mainly by thermoactivated hoppings between minima of the periodic potential along the tube axis. The rate hoppings is substantially depends on temperature because of thermal fluctuations of tube wall.
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2.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Serzhantova M. V., Kuzubov A. A., Fedorov A. S., Krasnov P. O., Tomilin F. N.
Заглавие : Theoretical study of the influence of vacancies on the electronic structure of a hexagonal boron nitride monolayer
Место публикации : J. Exp. Theor. Phys.: MAIK NAUKA/INTERPERIODICA/SPRINGER, 2011. - Vol. 112, Is. 4. - P664-667. - ISSN 1063-7761, DOI 10.1134/S1063776111030150
Примечания : Cited References: 19
Предметные рубрики: INITIO MOLECULAR-DYNAMICS
TRANSITION
ALGORITHM
METALS
ENERGY
Ключевые слова (''Своб.индексиров.''): defect type--divacancies--forbidden band--hexagonal boron nitride--inhomogeneous distribution--nitrogen vacancies--spin densities--theoretical study--vacant levels--boron nitride--defects--deformation--density functional theory--electronic properties--electronic structure--magnetic moments--monolayers--nitrides--boron
Аннотация: The influence of boron and nitrogen vacancies and divacancies on the electronic structure of a hexagonal boron nitride h-BN monolayer is studied. In the presence of vacancies in the structure, the introduced states appear in the forbidden band. The position of an introduced state with respect to the upper occupied level and the lower vacant level depends on deformation. Calculations show that, depending on the defect type and the magnitude of the applied deformation, the introduced state can be both localized and not localized on atoms surrounding the defect. When the state is localized in the system, the inhomogeneous distribution of the spin density is observed, resulting in the appearance of the magnetic moment in the system.
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3.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Arauzo A., Kazak N. V., Ivanova N. B., Platunov M. S., Knyazev Yu. V., Bayukov O. A., Bezmaternykh L. N., Lyubutin I. S., Frolov K. V., Ovchinnikov S. G., Bartolome J.
Заглавие : Spin-glass behavior in single crystals of hetero-metallic magnetic warwickites MgFeBO4, Mg0.5Co0.5FeBO4, and CoFeBO4
Коллективы : MINECO Project [MAT11/23791, MAT2014-53921-R], DGA IMANA project [E-34], Russian Foundation for Basic Research [13-02-00958, 13-02-00358, 14-02-31051-mol-a], Council for Grants of the President of the Russian Federation [NSh-2886.2014.2, SP-938.2015.5], program of Foundation for Promotion of Small Enterprises in Science and Technology ("UMNIK" program)
Место публикации : J. Magn. Magn. Mater.: Elsevier Science, 2015. - Vol. 392. - P.114-125. - ISSN 0304-8853, DOI 10.1016/j.jmmm.2015.05.006. - ISSN 18734766(eISSN)
Примечания : Cited References:36. - This work has been financed by the MINECO Project MAT11/23791, MAT2014-53921-R and DGA IMANA project E-34, Russian Foundation for Basic Research (project Nr. 13-02-00958, 13-02-00358 and 14-02-31051-mol-a), Council for Grants of the President of the Russian Federation (project Nr. NSh-2886.2014.2 and SP-938.2015.5). The work of one of coauthors (M.S.P.) was supported by the program of Foundation for Promotion of Small Enterprises in Science and Technology ("UMNIK" program).
Предметные рубрики: SYSTEMS
CHAIN
Fe
SUSCEPTIBILITY
Fe2OBO3
ENERGY
Ключевые слова (''Своб.индексиров.''): warwickites--spin glass--entanglement--exchange interaction
Аннотация: Magnetic properties of heterometallic warwickites MgFeBO4, Mg0.5Co0.5FeBO4, and CoFeBO4 are presented, highlighting the effect of Co substitution on the magnetic properties of these compounds. The analysis of magnetization and heat capacity data has shown that these compounds exhibit a spin-glass transition below TSG=10, 20 and 22 K, respectively. Using zero field ac susceptibility as entanglement witness we find that the low dimensional magnetic behavior above TSG show quantum entanglement behavior χ(Τ)∝T−α(Τ) up to TE≈130 K. The α parameters have been deduced as a function of temperature and Co content, indicating the existence of random singlet phase in this temperature region. Above TE the paramagnetism is interpreted in terms of non-entangled spins giving rise to Curie–Weiss paramagnetism. The different intra- and inter-ribbon exchange interaction pathways have been calculated within a simple indirect coupling model. It is determined that the triangular motifs in the warwickite structure, together with the competing interactions, induce frustration. The spin-glass character is explained in terms of the substitutional disorder of the Mg, Fe and Co atoms at the two available crystallographic sites, and the frustration induced by the competing interactions. The Co substitution induces uniaxial anisotropy, increases the absolute magnetization and increases the spin-glass freezing temperature. The entanglement behavior is supported in the intermediate phase irrespective of the introduction of anisotropy by the Co substitution.Представлены магнитные свойства гетерометаллических варвикитов MgFeBO4, Mg0.5Co0.5FeBO4 и CoFeBO4, с выделением эффекта замещения Co на магнитные свойства этих соединений. Анализ данных намагниченности и теплоемкости показал, что эти соединения обладают спин-стекольным переходом ниже TSG=10, 20 и 22 К соответственно. Используя нулевого поля для переменной восприимчивости, мы находим, что низкоразмерных магнитное поведение выше TSG показать квантовая запутанность поведение χ (Τ) αT? α (Τ) до TEE130 К. Параметры α были выведены в зависимости от температуры и содержание Со, что указывает на существование случайного синглетного фазы в этой области температур. Над TE в Парамагнетизм интерпретируется в терминах перепутывания спинов, приводящих к парамагнетизму Кюри-Вейсса. Различные внутри- и обменного взаимодействия между направлениями были рассчитаны в модели простой косвенной связи. Установлено, что треугольные мотивы в структуре варвикита, вместе с конкурирующими взаимодействиями, вызывают фрустрацию. Характер спинового стекла объясняется в условиях беспорядка замещения атомов Mg, Fe и Co в двух доступных кристаллографических позициях, и фрустрацию, индуцированную конкурирующими взаимодействиями. Замена Со вызывает одноосную анизотропию, увеличивает абсолютную намагниченность и повышает температуру замерзания спинового стекла. Запутанность Поведения поддерживается в промежуточной фазе, независимо от анизотропии из-за введения замещения Со.
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4.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Qiao, Jianwei, Ning, Lixin, Molokeev M. S., Chuang, Yu-Chun, Zhang, Qinyuan, Poeppelmeier, Kenneth R., Xia, Zhiguo
Заглавие : Site-Selective Occupancy of Eu2+ Toward Blue-Light-Excited Red Emission in a Rb3YSi2O7:Eu Phosphor
Место публикации : Angew. Chem. - 2019. - Vol. 131, Is. 33. - P.11645-11650. - ISSN 1521-3757, DOI 10.1002/ange.201905787
Примечания : Cited References: 41. - This work is supported by the National Natural Science Foundation of China (51722202, 51572023, and 11574003), Natural Science Foundations of Beijing (2172036), Fundamental Research Funds for the Central Universities (FRF-TP-18-002C1), and the Guangdong Provincial Science & Technology Project (2018A050506004). K.R.P. recognizes that this work was made possible by support from the National Science Foundation, Solid State Materials Chemistry award DMR-1608218.
Предметные рубрики: LUMINESCENCE PROPERTIES
CE3+
ENERGY
PHOTOLUMINESCENCE
TRANSITION
Аннотация: Establishing an effective design principle in solid-state materials for a blue-light-excited Eu2+-doped red-emitting oxide-based phosphors remains one of the significant challenges for white light-emitting diodes (WLEDs). Selective occupation of Eu2+ in inorganic polyhedra with small coordination numbers results in broad-band red emission as a result of enhanced crystal-field splitting of 5d levels. Rb3YSi2O7:Eu exhibits a broad emission band at λmax=622 nm under 450 nm excitation, and structural analysis and DFT calculations support the concept that Eu2+ ions preferably occupy RbO6 and YO6 polyhedra and show the characteristic red emission band of Eu2+. The excellent thermal quenching resistance, high color-rendering index Ra (93), and low CCT (4013 K) of the WLEDs clearly demonstrate that site engineering of rare-earth phosphors is an effective strategy to target tailored optical performance.
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5.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Qiao, Jianwei, Ning, Lixin, Molokeev M. S., Chuang, Yu-Chun, Zhang, Qinyuan, Poeppelmeier, Kenneth R., Xia, Zhiguo
Заглавие : Site-Selective Occupancy of Eu2+ Toward Blue-Light-Excited Red Emission in a Rb3YSi2O7:Eu Phosphor
Место публикации : Angew. Chem. Int. Edit. - 2019. - Vol. 58, Is. 33. - P.11521-11526. - ISSN 1433-7851, DOI 10.1002/anie.201905787. - ISSN 1521-3773(eISSN)
Примечания : Cited References: 41. - This work is supported by the National Natural Science Foundation of China (51722202, 51572023, and 11574003), Natural Science Foundations of Beijing (2172036), Fundamental Research Funds for the Central Universities (FRF-TP-18-002C1), and the Guangdong Provincial Science & Technology Project (2018A050506004). K.R.P. recognizes that this work was made possible by support from the National Science Foundation, Solid State Materials Chemistry award DMR-1608218.
Предметные рубрики: LUMINESCENCE PROPERTIES
CE3+
ENERGY
PHOTOLUMINESCENCE
TRANSITION
Аннотация: Establishing an effective design principle in solid-state materials for a blue-light-excited Eu2+-doped red-emitting oxide-based phosphors remains one of the significant challenges for white light-emitting diodes (WLEDs). Selective occupation of Eu2+ in inorganic polyhedra with small coordination numbers results in broad-band red emission as a result of enhanced crystal-field splitting of 5d levels. Rb3YSi2O7:Eu exhibits a broad emission band at λmax=622 nm under 450 nm excitation, and structural analysis and DFT calculations support the concept that Eu2+ ions preferably occupy RbO6 and YO6 polyhedra and show the characteristic red emission band of Eu2+. The excellent thermal quenching resistance, high color-rendering index Ra (93), and low CCT (4013 K) of the WLEDs clearly demonstrate that site engineering of rare-earth phosphors is an effective strategy to target tailored optical performance.
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6.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Aplesnin S. S.
Заглавие : Quantum Monte Carlo investigation of the 2D Heisenberg model with S=1/2
Место публикации : Phys. Solid State: MAIK NAUKA/INTERPERIODICA/SPRINGER, 1999. - Vol. 41, Is. 1. - P103-107. - ISSN 1063-7834, DOI 10.1134/1.1130737
Примечания : Cited References: 33
Предметные рубрики: SQUARE-LATTICE
GROUND-STATE
SPIN-CORRELATIONS
ANTIFERROMAGNET
LA2CUO4
EU2CUO4
ENERGY
ORDER
Аннотация: The two-dimensional (2D) Heisenberg model with anisotropic exchange (Delta=1-J(x)/J(z)) and S=1/2 is investigated by the quantum Monte Carlo method. The energy, susceptibility, specific heat, spin-spin correlation functions, and correlation radius are calculated. The sublattice magnetization (sigma) and the Neel temperature of the anisotropic antiferromagnet are logarithmic functions of the exchange anisotropy: 1/sigma + 1 + 0.13(1) ln(1/Delta). Crossover of the static magnetic structural factor as a function of temperature from power-law to exponential occurs for T(c)/J approximate to 0.4. The correlation radius can be approximated by 1/xi =2.05T(1.0(6))/exp(1.0(4)/ T). For La(2)CuO(4) the sublattice magnetization is calculated as sigma=0.45, the exchange is J=(1125=1305) K; for Er(2)CuO(4)J similar to 625 K and the exchange anisotropy Delta similar to 0.003. The temperature dependence of the static structural magnetic factor and the correlation radius above the Neel temperature in these compounds can be explained by the formation of topological excitations (spinons). (C) 1999 American Institute of Physics. [S1063-7834(99)02401-6].
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7.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Kuzubov A. A., Eliseeva N. S., Krasnov P. O., Tomilin F. N., Fedorov A. S., Tolstaya A. V.
Заглавие : Possibility of a 2D SiC monolayer formation on Mg(0001) and MgO(111) substrates
Место публикации : Russ. J. Phys. Chem. A: MAIK Nauka-Interperiodica / Springer, 2013. - Vol. 87, Is. 8. - P.1332-1335. - ISSN 0036-0244, DOI 10.1134/S0036024413080141
Примечания : Cited References: 25
Предметные рубрики: AB-INITIO
THIN-FILMS
NANOTUBES
ENERGY
Ключевые слова (''Своб.индексиров.''): silicon carbide monolayer--density functional theory
Аннотация: The geometrical characteristics of a 2D SiC monolayer on Mg(0001) and MgO(111) plates regarded as potential materials for growing two-dimensional silicon carbide were studied. The most favorable positions of the atoms of 2D SiC on the substrates were determined. In the 2D SiC/Mg(0001) system, unlike in 2D SiC/MgO(111), the deviation of the carbon atom from the silicon carbide monolayer was insignificant (0.08 ). Consequently, magnesium can be used as a substrate for growing two-dimensional silicon carbide. The use of MgO(111) is not recommended because of a significant distortion of the 2D SiC surface.
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8.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Kuzubov A. A., Krasnov P. O., Kozhevnikova T. A., Popov M. N., Artyushenko P. V.
Заглавие : Peculiarities of the decoration of carbon nanotubes with transition metal atoms
Место публикации : Russ. J. Phys. Chem. B: MAIK NAUKA/INTERPERIODICA/SPRINGER, 2011. - Vol. 5, Is. 1. - P163-167. - ISSN 1990-7931, DOI 10.1134/S1990793111010076
Примечания : Cited References: 12. - The authors thank Interdepartmental Supercomputer Center, Russian Academy of Sciences, for the possibility of using a cluster computer, and Siberian Federal University for providing a supercomputer, on which quantum-chemical calculations were performed. This work was financially supported by the Analytic Departmental Special-Purpose Program "The Development of the Scientific Potential of the Higher School (2009-2010)" (project no. 2.1.1/2584).
Предметные рубрики: INITIO MOLECULAR-DYNAMICS
SURFACE
ENERGY
Ключевые слова (''Своб.индексиров.''): carbon nanotubes--decoration--transition metal atoms--carbon nanotubes--decoration--transition metal atoms
Аннотация: Carbon nanotubes decorated with transition metal, in particular, scandium, titanium, and vanadium, atoms offer promise for use in various applied science fields. We report the results of quantum-chemical calculations of the structure of the metallic layer of atoms of these metals coating the surface of (9, 0) and (10, 0) carbon nanotubes. It was shown that uniform one-layer coating by scandium and titanium could form on nanotubes with diameters no less than the diameter of (10, 0) nanotubes. Vanadium atoms could not uniformly cover nanotubes irrespective of their diameters.
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9.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Edel'man I. S., Petrov D. A., Ivantsov R. D., Zharkov S. M., Khaibullin R. I., Valeev V. F., Nuzhdin V. I., Stepanov A. L.
Заглавие : Microstructure and Magnetooptics of Silicon Oxide with Implanted Nickel Nanoparticles
Разночтения заглавия :авие SCOPUS: Microstructure and magnetooptics of silicon oxide with implanted nickel nanoparticles
Место публикации : J. Exp. Theor. Phys.: MAIK NAUKA/INTERPERIODICA/SPRINGER, 2011. - Vol. 113, Is. 6. - P1040-1049. - ISSN 1063-7761, DOI 10.1134/S1063776111160035
Примечания : Cited References: 44. - This work was supported by the Russian Foundation for Basic Research (project nos. 11-02-00972, 11-02-90420, 11-02-91341) and the program Research and Scientific-Pedagogical Brainpower of Innovated Russia (State contract 02.740.11.0797).
Предметные рубрики: SIMPLE METAL-CLUSTERS
OPTICAL-PROPERTIES
ION-IMPLANTATION
FARADAY-ROTATION
KERR SPECTRA
GLASS
RESONANCE
PHYSICS
ENERGY
FE
Ключевые слова (''Своб.индексиров.''): disperse structure--effective medium model--implanted samples--irradiation dose--magnetic circular dichroisms--magnetic nickel--magneto-optical faraday effect--magneto-optical measurements--matrix--metal nanoparticles--metallic nickel--nickel nanoparticles--nickel particles--optical range--spectral dependences--surface plasma resonances--tensor components--thin near-surface layers--amorphous silicon--crystal microstructure--dichroism--faraday effect--ion implantation--magnetoplasma--metallic compounds--nanomagnetics--nanoparticles--nickel--silicon compounds--silicon oxides--spectroscopy--tensors--transmission electron microscopy--nickel oxide
Аннотация: Metallic nickel nanoparticles of various sizes are formed in a thin near-surface layer in an amorphous SiO2 matrix during 40-keV Ni+ ion implantation at a dose of (0.25-1.0) x 10(17) ions/cm(2). The micro-structure of the irradiated layer and the crystal structure, morphology, and sizes of nickel particles formed at various irradiation doses are studied by transmission electron microscopy and electron diffraction. The magnetooptical Faraday effect and the magnetic circular dichroism in an ensemble of nickel nanoparticles are studied in the optical range. The permittivity (epsilon) over cap tensor components are calculated for the implanted samples using an effective medium model with allowance for the results of magnetooptical measurements. The spectral dependences of the tensor (epsilon) over cap components are found to be strongly different from those of a continuous metallic nickel film. These differences are related to a disperse structure of the magnetic nickel phase and to a surface plasma resonance in the metal nanoparticles.
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10.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Fedorov A. S., Avramov P. V., Ovchinnikov S. G., Kresse G.
Заглавие : Isotope velocity differentiation in thin carbon nanotubes through quantum diffusion
Место публикации : Europhys. Lett. - 2003. - Vol. 63, Is. 2. - P.254-260. - ISSN 0295-5075, DOI 10.1209/epl/i2003-00512-5
Примечания : Cited References: 17
Предметные рубрики: MOLECULAR-DYNAMICS
TRANSITIONS
TRANSPORT
ENERGY
Аннотация: An approach is proposed to evaluate the average velocities of adsorbate molecules in one-dimensional nanopore, when quantum tunneling between neighboring potential minima leads to nonzero velocity. The approach is used to calculate the hydrogen isotope molecule (H-2, D-2, T-2) velocities in ultrathin carbon single-wall nanotubes (SWNT) (3, 3) and (6, 0). It is shown that the isotope mass difference leads to large differences of the quantum tunneling value and large differences of the average molecule velocities, especially inside the tube (6, 0). It is shown that different tube chirality leads to drastically different velocities of adsorbate molecules, even if the diameters of both nanotubes do not differ significantly.
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11.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Krasnov P. O., Eliseeva N. S., Kuzubov A. A.
Заглавие : Interaction of Scandium and Titanium Atoms with a Carbon Surface Containing Five- and Seven-Membered Rings
Коллективы : Ministry of Education and Science of the Russian Federation
Место публикации : J. Exp. Theor. Phys.: MAIK Nauka-Interperiodica / Springer, 2012. - Vol. 114, Is. 1. - P.80-84. - ISSN 1063-7761, DOI 10.1134/S1063776111160059. - ISSN 1090-6509
Примечания : Cited References: 25. - We are grateful to the Joint Supercomputer Center, Russian Academy of Sciences, for the possibility of using the computer cluster for our quantum-chemical calculations. This work was supported by the Ministry of Education and Science of the Russian Federation (federal program "Human Capital for Science and Education in Innovative Russia" for 2009-2013).
Предметные рубрики: MOLECULAR-HYDROGEN COMPLEXES
STORAGE
NANOTUBES
TRANSITION
ENERGY
TEMPERATURE
EXCHANGE
DYNAMICS
METALS
C60
Аннотация: The use of carbon nanotubes coated by atoms of transition metals to store molecular hydrogen is associated with the problem of the aggregation of these atoms, which leads to the formation of metal clusters. The quantum-chemical simulation of cluster models of the carbon surface of a graphene type with scandium and titanium atoms has been performed. It has been shown that the presence of five- and seven-membered rings, in addition to six-membered rings, in these structures makes it possible to strongly suppress the processes of the migration of metal atoms over the surface, preventing their clustering.
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12.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Zhu L., Huang Z., Molokeev M. S., Min X., Liu Y., Fang M., Wu X.
Заглавие : Influence of cation substitution on the crystal structure and luminescent properties in apatite structural Ba4.97- xSrx(PO4)3Cl:0.03Eu2+ phosphors
Место публикации : Chem. Phys. Lett.: Elsevier, 2016. - Vol. 658. - P.248-253. - ISSN 00092614 (ISSN), DOI 10.1016/j.cplett.2016.06.061
Примечания : Cited References: 23. - This present work was supported by the National Natural Science Foundations of China (Grant Nos. 51472222 and 51372232), the Fundamental Research Funds for the Central Universities (Grant No. 2652015310), and the Research Fund for the Doctoral Program of Higher Education of China (Grant No. 20130022110006).
Предметные рубрики: PHOTOLUMINESCENCE
ENERGY
Ce3+
Sr
UV
Ключевые слова (''Своб.индексиров.''): substitution--apatite--ba4.97- xsrx(po4)3cl:0.03eu2+--luminescence
Аннотация: A series of apatite-type phosphors Ba4.97- xSrx(PO4)3Cl:Eu2+(x = 0, 0.5, 1.0, 1.5, 2.0) were synthesized by the high temperature solid-state reaction method, and its luminescence properties were investigated in detail. It can be found that a red shift of the emission peak wavelength emerged from 439 to 462 nm with the continuous introduction of Sr2+ into the crystal lattice which has been simulated by a crystal-field model. The red shift is explained by the distortion in the crystal structure through X-ray diffraction and the Rietveld refinement analysis. According to a recently raised structural model, Eu2+ ions are surrounded by O atoms, PO4 tetrahedrons and Ba/Sr ions. After introducing Sr2+ into the lattice, the interatomic distance between Ba/Sr atoms and Eu2+ was expected to become shorter, resulting in a distortion of the inner EuOn polyhedrons. Then the crystal field strength surrounding Eu2+ was increased, finally resulting in the red shift. © 2016 Published by Elsevier B.V.
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13.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Ovchinnikov S. G., Antipina L. Yu., Tomilin F. N., Kuzubov A. A.
Заглавие : Effect of electron correlations on the structure of photoprotein substrates
Коллективы :
Место публикации : JETP Letters. - 2010. - Vol. 91, Is. 9. - P.490-493. - ISSN 0021-3640, DOI 10.1134/S0021364010090122
Примечания : Cited References: 14. - This work was supported by the Russian Foundation for Basic Research (project no. 07-04-00930-a), by the Presidium of the Russian Academy of Sciences (program "Molecular and Cellular Biology"), and by the Siberian Branch, Russian Academy of Sciences (project no. 2).
Предметные рубрики: ANGSTROM RESOLUTION
CRYSTAL-STRUCTURE
AEQUORIN
ENERGY
OBELIN
GAS
Аннотация: The electronic structure and total energy of various isomeric forms of coelenterazine and coelenteramide have been calculated by quantum chemistry methods both in the single-electron approximation and taking into account correlation effects. It has been shown that the inclusion of electron correlations makes it possible to obtain the structure of the coelenteramide close to the experimentally determined structure, as well as to choose the structure of the coelenterazine CLZ(1H) as the most probable isomeric form.
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14.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Fedorov A. S., Ovchinnikov S. G.
Заглавие : Density and thermodynamics of hydrogen adsorbed inside narrow carbon nanotubes
Разночтения заглавия :авие SCOPUS: Density and Thermodynamics of Hydrogen Adsorbed Inside Narrow Carbon Nanotubes
Место публикации : Phys. Solid State: AMER INST PHYSICS, 2004. - Vol. 46, Is. 3. - P584-589. - ISSN 1063-7834, DOI 10.1134/1.1687883
Примечания : Cited References: 21. - This study was supported by the federal program “Integration,” project no. Б0017
Предметные рубрики: MOLECULAR-DYNAMICS
TRANSITIONS
TRANSPORT
ENERGY
TUBES
Аннотация: A model is proposed for calculating the thermodynamic functions and the equilibrium density of a one-dimensional chain of molecules (atoms) adsorbed inside a narrow nanotube. The model considers both the interaction between introduced atoms (molecules) and their interaction with the nanotube walls. The quantum-mechanical effects resulting in discrete energy levels of a particle and in its smeared position between neighbors are taken into account. In calculating the free energy at a nonzero temperature, the phonon contribution and the particle transitions to excited levels are considered. The model is applied to calculate the thermodynamic parameters of adsorbed hydrogen molecules inside extremely narrow single-wall carbon nanotubes of the (3,3) and (6,0) type. It is shown that external pressure gives rise to a sequence of first-order phase transitions, which change the density of adsorbed hydrogen molecules. (C) 2004 MAIK "Nauka / Interperiodica".
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15.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : ZINENKO V. I., FEDOROV A. S.
Заглавие : CALCULATION OF LONG-WAVELENGTH PHONON FREQUENCIES, OF DIELECTRIC PERMITTIVITY, AND B1-B2 PHASE-TRANSITIONS IN ALKALI-METAL HYDRIDES BY THE DENSITY-FUNCTIONAL TECHNIQUE
Место публикации : Fiz. Tverd. Tela: MEZHDUNARODNAYA KNIGA, 1994. - Vol. 36, Is. 5. - P1357-1365. - ISSN 0367-3294
Примечания : Cited References: 17
Предметные рубрики: PRESSURE
ENERGY
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16.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Fedorov D.G., Kitaura K., Avramov P. V., Jensen J.H.
Заглавие : Analytic gradient for the adaptive frozen orbital bond detachment in the fragment molecular orbital method
Место публикации : Chem. Phys. Lett. - 2009. - Vol. 477, Is. 1-3. - P.169-175. - JUL 28. - ISSN 0009-2614, DOI 10.1016/j.cplett.2009.06.072
Примечания : Cited Reference Count: 49. - Гранты: We thank Professor M. Suenaga of Kyushu University for continuing his development of the modeling software FACIO and its FMO interface. D. G. F. and K. K. were supported by the a Grant-in- Aid for Scientific Research (JSPS, Japan) and the Next Generation SuperComputing Project, Nanoscience Program (MEXT, Japan). J.H.J. was supported by a Skou Fellowship from the Danish Research Agency (Forskningsradet for Natur og Univers).Финансирующая организация: JSPS, Japan; Next Generation SuperComputing Project; MEXT, Japan; Danish Research Agency
Предметные рубрики: DENSITY-FUNCTIONAL THEORY
GEOMETRY OPTIMIZATIONS
SEMICONDUCTOR NANOWIRES
SILICON NANOWIRES
METHOD FMO
ENERGY
SURFACES
RECONSTRUCTION
CHEMISTRY
PROTEINS
Ключевые слова (''Своб.индексиров.''): energy gradients--fragment molecular orbital methods--future applications--geometry optimization--numerical criteria--silicon nanowires--molecular modeling--molecular orbitals
Аннотация: We have developed and implemented the analytic energy gradient for the bond detachment scheme in the fragment molecular orbital method (FMO) suitable to describe solids, and applied it to the geometry optimization of a silicon nanowire at several levels of theory. In addition, we have examined in detail the effects of the particular choice of the fragmentation upon the accuracy and introduced a number of numerical criteria to characterize the errors. The established route is expected to provide guidance for future applications of FMO to surfaces, solids and nanosystems. (C) 2009 Elsevier B. V. All rights reserved.
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17.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Fedorov A. S., Sadreev A. F.
Заглавие : Ab-initio investigation of thermoactivated directional transport of hydrogen molecules inside narrow carbon nanotubes
Место публикации : Phys. Status Solidi B. - 2009. - Vol. 246: 23rd Winterschool on Electronic Properties of Novel Materials (MAR 14, 2009, Kirchberg, GERMANY), Is. 11. - P.2598-2601. - ISSN 0370-1972, DOI 10.1002/pssb.200982285
Примечания : Cited References: 21. - A.S.Fedorov thanks the Institute of Computer Modeling (Krasnoyarsk, Russia) and the Joint Supercomputer Center (Moscow) for an assistence in quantum chemical calculations.
Предметные рубрики: DIFFUSION
ENERGY
Аннотация: Using the pseudopotential DFT and the empirical potential methods we calculate the potential acting to the hydrogen molecules in narrow single-wall carbon nanotubes (SWCNT) (6,0),(7,0) and (3,3). The potential forms a goffered potential surface and can be approximated as V(z, r, phi) approximate to V(0) sin(2 pi z/a) + V(r). We show that in these SWCNTs transport of molecules is given mainly by thermoactivated hoppings between minima of the periodic potential along the tube axis. Taking into account that hydrogen density distribution inside nanotube is stationary and assuming the temperature is changed linearly along the SWCNT length we show that the H(2) density is sufficiently variated, especially for the case of (6,0)SWCNT where the density on both SWCNT ends are different at similar to 30 times when the temperature is changed along the SWCNT from 300K to 1200K. Suppose that H2 molecules can penetrate in the both open SWCNT ends, the molecules would move in the direction of the temperature decreasing. This effect may be used potentially to build up a molecular pump driven by the temperature gradient along narrow nanotube. (C) 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
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18.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Fedorov A. S., Sorokin P. B., Kuzubov A. A.
Заглавие : Ab initio study of hydrogen chemical adsorption on platinum surface/carbon nanotube join system
Место публикации : Phys. Status Solidi B. - 2008. - Vol. 245, Is. 8. - P.1546-1551. - ISSN 0370-1972, DOI 10.1002/pssb.200844155
Примечания : Cited References: 31
Предметные рубрики: WALLED CARBON NANOTUBES
MOLECULAR-DYNAMICS
ROOM-TEMPERATURE
STORAGE
ENERGY
THERMODYNAMICS
GRAPHITE
DENSITY
POINTS
Аннотация: The process of hydrogen chemical adsorption on platinum cluster/single wall carbon nanotube (CNT) join surfaces is modelled at various temperatures and pressures. For that, the adsorption energy of hydrogen atoms on surfaces of both platinum (111) plate and CNT (5,5) or (8,8) types is calculated by density functional theory with the PBE approximation. At various temperatures the hydrogen atom hopping rate on both platinum and CNT surfaces is calculated by the transition state theory. Furthermore the hydrogen hopping rate from the platinum surface to the attached nanotube is obtained by calculation of the total energy profile. It is proved that hydrogen atoms can migrate easily at the platinum surface at all temperatures, but at the CNT surface they can migrate beginning at 400-500 K. By calculation of chemical potentials of hydrogen in gas or on CNT or platinum cluster surfaces the equilibrium density of adsorbed hydrogen was calculated at different temperatures and pressures. It is established that for all temperatures in the range 300-900 K and for all pressures less than 500 bar, the hydrogen is dissociated and chemically adsorbed on the platinum surface very effectively, but surface site occupation by hydrogen on attached CNT surface is rather small. But if CNT vacancies are present in the tube structure and the temperature is lower then 450 K, hydrogen atoms can be adsorbed effectively enough on these vacancies. (C) 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
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