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61.
Photoabsorption and photoluminescence properties of nonbridging oxygen -O-Ge[triple bond](NBO), -OO-Ge[triple bond] (peroxy radical), O=Ge=, and (O2)Ge= defects in germanium oxides have been investigated by high-level ab initio calculations. Geometry optimization for excited electronic states of model clusters simulating these defects was carried out at the complete-active-space self-consistent-field level, and relative energies were calculated by various methods including time-dependent density-functional theory, outer-valence Green's functions, equation-of-motion coupled cluster theory with single and double excitations, symmetry-adapted cluster configuration interaction, multireference second-order perturbation theory, and multireference configuration interaction. The results demonstrate that the considered excited states of the aforementioned defects normally exhibit large Stokes shifts and that, with few exceptions, UV photoabsorption is accompanied by red or IR photoluminescence. 相似文献
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T. S. Zyubina A. S. Zyubin Yu. A. Dobrovolsky V. M. Volokhov 《Russian Chemical Bulletin》2016,65(3):621-630
To search for advanced anode materials for Li-ion rechargeable batteries, the structures, stabilities, and electronic properties of crystalline silicon and those of the snowball-type (SB) and core-shell (CS) silicon clusters Sizyubin@icp.ac.ru (n = 2—308) were quantum chemically modeled within the framework of the density functional theory with inclusion of gradient correction and periodic boundary conditions. The formation of SB agglomerates from smaller Sizyubin@icp.ac.ru clusters (n ≤ 7) is energetically preferable. At n ≥ 105 and circumscribed sphere diameters (D) ≥ 17—20 Å, CS isomers comprised of quasi-crystalline cores surrounded by small clusters are energetically more favorable than the SB isomers. 相似文献
65.
T. S. Zyubina L. V. Shmygleva R. V. Pisarev A. S. Zyubin A. V. Pisareva Yu. A. Dobrovolsky V. M. Volokhov 《Russian Chemical Bulletin》2017,66(1):62-69
The structures of crystalline hydrates of calix[4]arene-para-sulfonic acid with n (n = 6–16) water molecules and the activation barriers to surface proton migration were calculated within the framework of the density functional theory (DFT) using the PBE gradient-corrected functional, the "hard" basis set of projector-augmented waves (PAW), a corresponding pseudopotential, periodic boundary conditions, and the VASP program package. The energies of formation of crystalline hydrates from calix[4]arene-para-sulfonic acid and n water molecules calculated per water molecule are in the range of 0.4–0.9 eV and depend on n. The adsorption energy of water on the surface is in the range of 0.5–0.7 eV. The activation barriers to proton transfer across the surface calculated for the most stable crystal (n = 8) are close to experimental data and depend on the number of superstoihiometric water molecules, being equal to ~0.2 eV provided three superstoihiometric water molecules per surface SO3H group. 相似文献
66.
A. S. Zyubin T. S. Zyubina Yu. A. Dobrovol’skii V. M. Volokhov 《Russian Journal of Inorganic Chemistry》2013,58(1):56-61
The interaction of Pt29 nanoparticles with pristine and reduced (110), (100), (011), and (001) SnO2 surfaces has been modeled using the density functional theory method within the generalized gradient approximation (GGA). It has been demonstrated that, in some cases, the reduction of the surface leads to a considerable increase in the energy of interaction with platinum. The second oxidation of such structures should lead to the platinum fixation on the surface. 相似文献
67.
D. V. Konev M. A. Vorotyntsev C. H. Devillers T. S. Zyubina A. S. Zyubin K. V. Lizgina A. G. Volkov 《Russian Journal of Electrochemistry》2013,49(8):753-758
It is shown that the derivatives of the source electroactive polymer, magnesium polyporphine (pMgP), can be synthesized by successive treatment of electropolymerized pMgP film on the electrode surface with trifluoroacetic acid and zinc acetate solutions in the organic solvents. Based on the electrochemical and spectral characteristics of the modifying layers, it is concluded that the central magnesium ion in the porphine monomeric blocks is replaced with the formation of polyporphine in the form of free base (pH2P) and zinc polyporphine, respectively. The oxidative transformation of thus obtained new polyporphines pH2P and pZnP (which are the polymers of type I) is realized. It leads to a change in the molecular structure of polymer films (the transition to the type II); as a result, the potential range of their electroactivity is extended significantly. 相似文献
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A. S. Zyubin T. S. Zyubina O. V. Kravchenko M. V. Solov’ev M. V. Tsvetkov A. A. Zaitsev Yu. A. Dobrovol’skii 《Russian Journal of Inorganic Chemistry》2018,63(2):201-212
The successive elimination of H2 from Mg(BH4)2 · nH2O (n = 1, 4, 6), (Mg(BH4)2)2 · 8H2O, and (Mg(BH4)2)4 · 4H2O complexes has been modeled in the framework of the cluster approach with the use of the 6-31G* basis set and hybrid density functional (B3LYP). It has been shown that the structures in which the proton-donating water molecule is located between two metal cations have the lowest potential barriers. The barrier to elimination of the first H2 molecule is low, but it increases as OH groups are substituted for the H atoms in the BH 4 ? anion. The elimination of H2 occurs with a considerable energy release. 相似文献
70.
S. A. Zyubin 《Algebra and Logic》2006,45(5):296-305
A subgroup having non-empty intersection with each class of conjugate elements of the group is said to be conjugately dense.
It is shown that, under certain conditions, the number of conjugately dense subgroups in a free product with amalgamation
is not less than some cardinal. As a consequence, P. Neumann’s conjecture in the Kourovka notebook (Question 6.38) is refuted.
It is also stated that a modular group and a non-Abelian group of countable or finite rank possess continuum many pairwise
non-conjugate conjugately dense subgroups.
Supported by RFBR grant No. 03-01-00905.
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Translated from Algebra i Logika, Vol. 45, No. 5, pp. 520–537, September–October, 2006. 相似文献