共查询到20条相似文献,搜索用时 0 毫秒
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V. S. Borisov S. D. Marchuk Ya. V. Ezhova S. S. Baryshnikov V. S. Marchuk L. A. Shcherbachenko 《Russian Physics Journal》2010,53(5):493-498
Experimental and theoretical investigations of the electret effect in low-dimensional micas with different degrees of dispersion
and adsorption are carried out at temperatures in the range 20–140°C. The results obtained allow the electric activity of
the mica particles comprised in these systems to be determined and the efficiency of application of low-dimensional micas
for fillers of composite materials to be estimated. 相似文献
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F. A. Kassan-Ogly B. N. Filippov 《Bulletin of the Russian Academy of Sciences: Physics》2010,74(10):1452-1454
On the basis of exact analytical solutions for spin-spin correlation functions in the one-dimensional 3-state [1] and 4-state
[2] standard Potts models and Ising model [3] with allowance for the interactions between nearest neighbors J and next-nearest neighbors J′, phenomena of the appearance and disappearance of frustrations have been investigated, depending on the signs of J and J′ and the ratio of the interactions. In the Ising model, these phenomena have been studied on triangular, hexagonal, and kagomé
lattices on the basis of exact analytical solutions for the maximum values of the Kramers-Wannier matrices obtained in [4,
5]. 相似文献
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R. Z. Vitlina L. I. Magarill A. V. Chaplik 《Journal of Experimental and Theoretical Physics》2008,106(4):793-799
The dispersion of plasma waves in systems of various dimensions is investigated up to the end point of the spectrum. In 2D and 3D systems, the plasmon spectrum still ends (due to Landau damping) within the applicability range of the quasi-classical approximation, i.e., for ?k ? p F (?k is the plasmon momentum and p F is the electron Fermi momentum). In 1D systems, the results are qualitatively different, since the Landau damping is concentrated in a region where the quantum effects cannot be ignored. This peculiarity of 1D systems gives rise to undamped branches of acoustic plasmons with a phase velocity lower than the electron Fermi velocity in multicomponent 1D plasmas. 相似文献
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Abhishek Dhar 《物理学进展》2013,62(5):457-537
Recent results on theoretical studies of heat conduction in low-dimensional systems are presented. These studies are on simple, yet non-trivial, models. Most of these are classical systems, but some quantum-mechanical work is also reported. Much of the work has been on lattice models corresponding to phononic systems, and some on hard-particle and hard-disc systems. A recently developed approach, using generalized Langevin equations and phonon Green's functions, is explained and several applications to harmonic systems are given. For interacting systems, various analytic approaches based on the Green–Kubo formula are described, and their predictions are compared with the latest results from simulation. These results indicate that for momentum-conserving systems, transport is anomalous in one and two dimensions, and the thermal conductivity κ diverges with system size L as κ ~ L α. For one-dimensional interacting systems there is strong numerical evidence for a universal exponent α = 1/3, but there is no exact proof for this so far. A brief discussion of some of the experiments on heat conduction in nanowires and nanotubes is also given. 相似文献
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Hassan SA Vasconcellos AR Mesquita MV Luzzi R 《Physical review. E, Statistical physics, plasmas, fluids, and related interdisciplinary topics》2000,61(1):71-76
The optical properties of low-dimensional carrier systems ("quantum wire" type) driven away from equilibrium are studied. The frequency and wave-vector-dependent dielectric function of a quasi-one-dimensional electron system under the action of an exciting external pumping source is derived. The optical responses of the system are obtained in terms of its nonequilibrium thermodynamic state, the latter characterized resorting to a nonequilibrium statistical ensemble formalism. 相似文献
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V. P. Kurbatsky 《Journal of Experimental and Theoretical Physics》2017,125(1):148-158
The dielectric tensor of a low-dimensional metal system has been introduced on the basis of the density matrix in the relaxation time approximation. The properties of this tensor have been analyzed. It has been proved that anisotropy and nonlocality are decisive features of the response of low-dimensional systems to an electromagnetic field. In particular, the expression has been derived for the dielectric tensor of nanometer- thick metal films. It has been shown that the dielectric tensor components can be reduced to the Drude dielectric function for a homogeneous metal in the case when the film thickness considerably exceeds the effective electron mean free path. The application of the classical distribution function for describing electrons in the film is justified under these conditions. 相似文献
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The light absorption and laser gain in quantum wells are calculated using the cumulant expansion method and the fluctuation-dissipation theorem with allowance made for the strong Coulomb interaction of charge carriers. It is shown that the multiplasmon transitions result in a smoothening of the absorption spectrum and a shift in the absorption edge toward the long-wavelength range. The theoretical laser gain spectra are in agreement with the available experimental data. For In0.05Ga0.95As quantum wells, the laser gain g = 50 cm?1 is reached at an electron density nd0 = 1.64 × 1012 cm?2. 相似文献
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《Physics letters. A》2004,320(4):254-260
We address a simple connection between results of Hamiltonian non-linear dynamical theory and thermostatistics. Using a properly defined dynamical temperature in low-dimensional symplectic maps, we display and characterize long-standing quasi-stationary states that eventually cross over to a Boltzmann–Gibbs-like regime. As time evolves, the geometrical properties (e.g., fractal dimension) of the phase space change sensibly, and the duration of the anomalous regime diverges with decreasing chaoticity. The scenario that emerges is consistent with the non-extensive statistical mechanics one. 相似文献
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《Solid State Communications》1998,107(11):623-628
Strongly correlated quantum systems in low dimensions often exhibit novel quantum ordering. This ordering is sometimes hidden and can be revealed only by examining new “dual” types of correlations. Such ordering leads to novel collection modes and fractional quantum numbers. Examples will be presented from quantum spin chains and the quantum Hall effect. 相似文献
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A. A. Akhkubekov A. M. Bagov 《Bulletin of the Russian Academy of Sciences: Physics》2009,73(7):905-907
The influence of electrotransfer on the macroscopic flow in Bi-Pb and Bi-Cd systems at contact melting has been experimentally studied. The electric current passing through the melt formed at contact melting is found to affect significantly the rate of current rise and additionally contributes to the velocity of inert label displacement. 相似文献
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V. L. Korenev 《JETP Letters》1999,70(2):129-134
A mechanism of dynamic self-polarization of nuclei is studied which is weakly temperature-dependent and operates efficiently
in low-dimensional systems (quantum wells, quantum dots). It is due to the hyperfine interaction of nuclei with excitons whose
spin polarization is artificially maintained at zero (by illuminating with unpolarized light) but for which nonequilibrium
alignment occurs. Nuclear self-polarization arises as a result of the conversion of the alignment of excitons into nuclear
orientation in the effective magnetic field of the polarized nuclei.
Pis’ma Zh. éksp. Teor. Fiz. 70, No. 2, 124–129 (25 July 1999) 相似文献
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D. Augier D. Poilblanc 《The European Physical Journal B - Condensed Matter and Complex Systems》1998,1(1):19-28
Properties of low-dimensional spin-Peierls systems are described by using a one-dimensional S
=1/2 antiferromagnetic Heisenberg chain linearly coupled to a single phonon mode of wave vector (whose contribution is expected to be dominant). By exact diagonalizations of small rings with up to 24 sites supplemented by a finite size scaling analysis, static and dynamical properties are investigated. Numerical evidences
are given for a spontaneous discrete symmetry breaking towards a spin gapped phase with a frozen lattice dimerization. Special
emphasis is put on the comparative study of the two inorganic spin-Peierls compounds CuGeO3 and NaV2O5 and the model parameters are determined from a fit of the experimental spin gaps. We predict that the spin-phonon coupling
is 2 or 3 times larger in NaV2O5 than in CuGeO3. Inelastic neutron scattering spectra are calculated and similar results are found in the single phonon mode approximation
and in the model including a static dimerization. In particular, the magnon S
=1 branch is clearly separated from the continuum of triplet excitations by a finite gap.
Received: 30 July 1997 / Revised: 16 September 1997 / Accepted: 10 October 1997 相似文献
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It is shown that the threshold interaction constant (TIC) αD for the existence of a condensed phase increases with the dimension D of a Bose system (α3 < α2 < α1). TICs are evaluated exactly for a wide class of two-parameter potentials (the latter may approximate real physical interactions). The results are applied to spin-polarized systems. The possibility of an electric field induced liquid-gas transition is discussed. The TIC for N-particle clusters diminishes with N. 相似文献
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B.S. Kandemir T. Altanhan 《The European Physical Journal B - Condensed Matter and Complex Systems》2002,27(4):517-526
We investigate the stability condition of large bipolarons confined in a parabolic potential containing certain parameters
and a uniform magnetic field. The variational wave function is constructed as a product form of electronic parts, consisting
of center of mass and internal motion, and a part of coherent phonons generated by Lee-Low-Pines transformation from the vacuum.
An analytical expression for the bipolaron energy is found, from which the ground and excited-state energies are obtained
numerically by minimization procedure. The bipolaron stability region is determined by comparing the bipolaron energy with
those of two separate polarons, which is already calculated within the same approximation. It is shown that the results obtained
for the ground state energy of bipolarons reduce to the existing works in zero magnetic field. In the presence of a magnetic
field, the stability of bipolarons is examined, for three types of low-dimensional system, as function of certain parameters,
such as the magnetic-field, the electron-phonon coupling constant, Coulomb repulsion and the confinement strength. Numerical
solutions for the energy levels of the ground and first excited states are examined as functions of the same parameters.
Received 7 March 2002 and Received in final form 22 April 2002 Published online 25 June 2002 相似文献
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Possibilities of spatial localization of spin-polarized electrons due to spin–orbit interaction are investigated theoretically. Situations most interesting for us are the ones where electrons of one spin state (helicity) are localized while the opposite helicity relates to extended wave functions. On examples of simplest short range potentials it is shown that such spin separation is, in principle, possible. Magnetic properties of electrons bound to a shallow 2D axially symmetric well are considered. Accounting for the spin–orbit contribution results in an anomalously large effective g-factor of this system. 相似文献
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基于密度泛函理论,选择generalized gradient approximation(缩写为GGA)交换作用势,使用自洽场全势的线性缀加平面波方法,计算了Cu原子组成的5种不同体系,包括面心立方晶体,两种原子面和两种原子链.结果显示,平面正六边形晶格要比正方形晶格从能量上更加稳定,原子最近邻距离稍长;而平面锯齿形原子链与直线形原子链相比也有类似的计算结果.计算还发现,锯齿形原子链中的电子态密度表现异常,能带出现间隙.另外,对比不同体系的态密度和结构,分析了量子限制和原子构型对体系电子性质的影响.
关键词:
原子链
电子结构
平面波方法
密度泛函理论 相似文献
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