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61.
62.
Alexander V. Evteev Leila Momenzadeh Elena V. Levchenko Irina V. Belova Graeme E. Murch 《哲学杂志》2013,93(34):3992-4014
An analytical treatment of decomposition of the phonon thermal conductivity of a crystal with a monatomic unit cell is developed on the basis of a two-stage decay of the heat current autocorrelation function observed in molecular dynamics simulations. It is demonstrated that the contributions from the acoustic short- and long-range phonon modes to the total phonon thermal conductivity can be presented in the form of simple kinetic formulas, consisting of products of the heat capacity and the average relaxation time of the considered phonon modes as well as the square of the average phonon velocity. On the basis of molecular dynamics calculations of the heat current autocorrelation function, this treatment allows for a self-consistent numerical evaluation of the aforementioned variables. In addition, the presented analysis allows, within the Debye approximation, for the identification of the temperature range where classical molecular dynamics simulations can be employed for the prediction of phonon thermal transport properties. As a case example, Cu is considered. 相似文献
63.
N. E. Sluchanko A. N. Azarevich A. V. Bogach V. V. Glushkov S. V. Demishev A. V. Levchenko V. B. Filippov N. Yu. Shitsevalova 《Journal of Experimental and Theoretical Physics》2013,116(5):866-871
The transverse magnetoresistance Δρ/ρ(H, T) of Tm1 ? x Yb x B12 single crystals is studied in the ytterbium concentration range corresponding to the antiferromagnet-paramagnet transition in a magnetic field up to 80 kOe at low temperatures. A magnetic H-T phase diagram is constructed for the antiferromagnetic state of substitutional Tm1 ? x Yb x B12 solid solutions with x ≤ 0.1. The contributions to the magnetoresistance in the antiferromagnetic and paramagnetic phases of the dodecaborides under study are separated. Along with negative quadratic magnetoresistance -Δρ/ρ ∝ H 2, the magnetically ordered phase of these compounds is found to have component Δρ/ρ ∝ H that linearly changes in a magnetic field. The negative contribution to the magnetoresistance of Tm1 ? x Yb x B12 is analyzed in terms of the Yosida model for a local magnetic susceptibility. 相似文献
64.
A. V. Bogach N. E. Sluchanko V. V. Glushkov S. V. Demishev A. N. Azarevich V. B. Filippov N. Yu. Shitsevalova A. V. Levchenko J. Vanacken V. V. Moshchalkov S. Gabani K. Flachbart 《Journal of Experimental and Theoretical Physics》2013,116(5):838-842
The magnetization of substitutional Tm1 ? x Yb x B12 solid solutions is studied in the composition range 0 < x ≤ 0.81. The measurements are performed at low temperatures (1.9–300 K) in steady (up to 11 T) and pulsed (up to 50 T, pulse duration of 20–100 ms) magnetic fields. An analysis of the experimental data allowed the contributions to the magnetization of the paramagnetic phase of the Tm1 ? x Yb x B12 compounds to be separated. These contributions include a Pauli component, which corresponds to the response of the heavy-fermion manybody states that appears in the energy gap in the vicinity of the Fermi level (density of states (3?4) × 1021 cm?3 meV?1), and a contribution with saturation in high magnetic fields attributed to the localized magnetic moments ((0.8–3.7)μB per unit cell) of the nanoclusters formed by rare-earth ions with an antiferromagnetic interaction. 相似文献
65.
A. Yu. Pryadilshchikov A. T. Kosilov A. V. Evteev E. V. Levchenko 《Journal of Experimental and Theoretical Physics》2008,107(3):430-434
Features of the formation of a percolation cluster structure composed of interpenetrating and contacting icosahedra during the glass transition in an amorphous Ni60Ag40 alloy have been studied using the molecular-dynamics method and statistical geometric analysis. Data on the morphology of clusters composed entirely of the interpenetrating icosahedra and on the character of their conjugation in the percolation cluster are presented. 相似文献
66.
K.S. Levchenko K.A. Chudov E.V. Zinoviev K.A. Lyssenko A.N. Fakhrutdinov D.U. Demin N.O. Poroshin P.S. Shmelin E.P. Grebennikov 《Tetrahedron letters》2019,60(23):1505-1508
A series of new chromophores based on 4-(dicyanomethylene)-2-vinyl 4H-chromenes was synthesized and their physical properties (UV–Vis, NMR, mass spectrometry) were studied. The chromophores show moderate or good solubility in organic solvents. Solvatochromism was investigated for compounds in solvents of low (1.4-dioxane, chlorobenzene, methylene chloride) and high polarity (acetone, acetonitrile). The calculations of the first hyperpolarizability (β) was performed using M052X/6-31+G(d) approximation. Chromophore’s molecules are characterized by high calculated values of the first hyperpolarizability (β) that is only 15% lower than that of FTC analogs. 相似文献
67.
Yuanlin Li Tianfang Zheng Yanxiang Liu Prof. Georgiy G. Levchenko Prof. Wei Han Prof. Aleksey V. Pashchenko Prof. Shin-ichi Sasaki Prof. Hitoshi Tamiaki Prof. Xiao-Feng Wang 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(56):e202201855
Hydrogen energy is an abundant, clean, sustainable and environmentally friendly renewable energy source. Therefore, the production of hydrogen by photocatalytically splitting water on semiconductors has been considered in recent years as a promising and sustainable strategy for converting solar energy into chemical energy to replace conventional energy sources and to solve the growing problem of environmental pollution and the global energy crisis. However, highly efficient solar-driven photocatalytic hydrogen production remains a huge challenge due to the poor visible light response of available photocatalytic materials and the low efficiency of separation and transfer of photogenerated electron-hole pairs. In the present work, organic heterojunction structures based on bacteriochlorophyll (BChl) and chlorophyll (Chl) molecules were introduced and used for solar-driven photocatalytic hydrogen production from water under visible light. Also, noble metal-free photocatalyst was successfully constructed on Ti3C2Tx nanosheets by simple successive deposition of Chl and BChl, which was used for the photocatalytic splitting water to hydrogen evolution reaction (HER). The results show that the optimal BChl@Chl@Ti3C2Tx composite has a high HER performance with 114 μmol/h/gcat, which is much higher than the BChl@Ti3C2Tx and Chl@Ti3C2Tx composites. 相似文献
68.
Mezhov-Deglin L. P. Levchenko A. A. Pel’menev A. A. Remizov I. A. 《Journal of Experimental and Theoretical Physics》2019,129(4):591-606
Journal of Experimental and Theoretical Physics - The conditions for the occurrence of an instability generated on the free surface of superfluid He-II by a constant or variable heat flux Q in the... 相似文献
69.
The recently introduced analytical model for the heat current autocorrelation function of a crystal with a monatomic lattice [Evteev et al., Phil. Mag. 94 (2014) p. 731 and 94 (2014) p. 3992] is employed in conjunction with the Green–Kubo formalism to investigate in detail the results of an equilibrium molecular dynamics calculations of the temperature dependence of the lattice thermal conductivity and phonon dynamics in f.c.c. Ni. Only the contribution to the lattice thermal conductivity determined by the phonon–phonon scattering processes is considered, while the contribution due to phonon–electron scattering processes is intentionally ignored. Nonetheless, during comparison of our data with experiment an estimation of the second contribution is made. Furthermore, by comparing the results obtained for f.c.c. Ni model to those for other models of elemental crystals with the f.c.c. lattice, we give an estimation of the scaling relations of the lattice thermal conductivity with other lattice properties such as the coefficient of thermal expansion and the bulk modulus. Moreover, within the framework of linear response theory and the fluctuation-dissipation theorem, we extend our analysis in this paper into the frequency domain to predict the power spectra of equilibrium fluctuations associated with the phonon-mediated heat dissipation in a monatomic lattice. The practical importance of the analytical treatment lies in the fact that it has the potential to be used in the future to efficiently decode the generic information on the lattice thermal conductivity and phonon dynamics from a power spectrum of the acoustic excitations in a monatomic crystal measured by a spectroscopic technique in the frequency range of about 1–20 THz. 相似文献
70.