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一维Anderson无序模型电子局域态 总被引:2,自引:1,他引:1
本文应用一种新方法,得到了包括次近邻相互作用,且无序点阵从五百到一万的一维安德逊无序模型电子本征态。结果表明此模型的本征态随着无序点阵的增加均从扩展态变为局域态,且变化的快慢受系统无序度的影响。 相似文献
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基于紧束缚模型,考虑无序的梯度衰减,研究了无序-有序二维介观环体系中无序梯度及结构尺寸等因素对持续电流的影响.在表面无序区无梯度衰减时,持续电流随无序度的变化先减小后增大,观察到类弹道和局域性的转变.当存在梯度衰减时,无序区部分区域无序度相应减小,对有序区产生较强散射,典型电流比没有无序衰减时偏小.有趣的是,当无序度指数衰减时,上述类弹道和局域性的转变却消失了,揭示了介观实验中能否观察到该转变与无序的梯度分布密切相关.此外,计算表明表面无序渗透的深度和环的宽度对持续电流也有重要影响,呈现奇异的量子尺寸效应.这不同于以前的理论预言.
关键词:
介观环
梯度无序
持续电流 相似文献
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本文建立了双层有机发光二极管中载流子的注入、输运和复合的理论模型.模型中采用了较合理的无序跳跃模型来处理界面问题.计算和讨论了空穴传输层厚度和内界面处的空穴势垒对器件复合效率和复合区域宽度的影响.结果表明:器件结构的变化导致电场强度在器件中的重新分布,空穴传输层厚度和内界面处空穴势垒的变化对器件的复合效率和复合区域宽度有重要影响. 相似文献
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George L. Strobel 《Zeitschrift für Physik A Hadrons and Nuclei》1972,256(3):210-225
Diffractive elastic scattering is studied by a boundary condition model that does not utilize a potential model.S-matrix elements are calculated and compared to those found from an optical potential model calculation. The unitarity of the model is related to the boundary condition imposed. A radially ingoing boundary condition is imposed on the wave function at one angle only, at a scattering angle of 180 °. This condition is required to hold in the vicinity of the nuclear radius, but not for all radii. Elastic scattering peaks at forward and backward angles are reproduced and discussed. The model is applied to composite particle scattering above the Coulomb barrier. 相似文献
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van Manen DJ Robertsson JO Curtis A 《The Journal of the Acoustical Society of America》2007,122(4):EL115-EL121
An exact boundary condition is presented for scattering problems involving spatially limited perturbations of arbitrary magnitude to a background model in generally inhomogeneous acoustic media. The boundary condition decouples the wave propagation on a perturbed domain while maintaining all interactions with the background model, thus eliminating the need to regenerate the wave field response on the full model. The method, which is explicit, relies on a Kirchhoff-type integral extrapolation to update the boundary condition at every time step of the simulation. The Green's functions required for extrapolation through the background model are computed efficiently using wave field interferometry. 相似文献
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《Revue Generale de Thermique》1998,37(5):371-383
The study of the equilibrium states of a homogeneous turbulence, in the absence of mean gradients, leads to an equilibrium solution with zero values for the turbulent scalar flows. Stability of this equilibrium solution is achieved by a simple condition on one of the coefficients of the model. A realisibility study of the turbulent scalar flow has been carried out an has led to a general realisibility condition imposed on the model coefficients. Moreover, it has been established that, if the return to isotropy is compatible with two supplementary constraints on the model coefficients, it is possible to substitute a sufficient yet much simpler condition for the general realisability condition. Finally, a numerical optimization on the basis of the experimental results and the direct simulation results, has proven that the proposed model ensures a better prediction of the scalar turbulence with respect to Rotta's model. 相似文献
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The purpose of this paper is to construct a general broadband impedance model, which is suited for predicting acoustic propagation problems in time domain.A multi-freedom broadband impedance model for sound propagation over impedance surfaces is proposed and the corresponding time domain impedance boundary condition is presented.Basing on the extended Helmholtz resonator,the multi-freedom impedance model is constructed through combing with a sum of rational functions in the form of general complex-conjugate pole-residue pairs and it is proved that the impedance model is well posed.The impedance boundary condition can be implemented into a computational aeroacoustics solver by a recursive convolution technique, which results in a fast and computationally efficient algorithm.The two dimensional and three dimensional benchmark problems are selected to validate the accuracy of the proposed impedance model and time domain simulations.The numerical results are in good agreement with the reference solutions.It is demonstrated that the proposed impedance model can be used to describe the broadband characteristics of acoustic liners,and the corresponding time domain impedance boundary condition is viable and accurate for the prediction of sound propagation over broadband impedance surfaces. 相似文献
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I.V. Belova 《哲学杂志》2013,93(7):665-675
The evolution of self-diffusion concentration depth profiles into a bulk polycrystalline material from a thin-film tracer source was studied using the lattice Monte Carlo method. The onset of the Type-B kinetics regime from the Type-A kinetics regime was investigated for a cubic grain model, which can be expected to capture the three-dimensional nature of the problem better than the usual grain boundary slab model. The solutions of Whipple–Le Claire (derived for the constant source condition), Suzuoka (derived for the instantaneous source condition), Bokstein and colleagues (derived for the constant source condition) and Levine and MacCallum (derived for the constant source condition) are tested. All these solutions describe the tail region of the profiles well for this model (provided that a simple empirical factor in the case of the first three solutions is introduced). The intermediate Type-AB kinetics regime proposed by Divinski and Larikov between the Type-A and Type-B kinetics regimes was also investigated but could not be located from analyses of best-fit exponents. Forcing the fitting nonetheless to the tail regions shows that their analysis needs some further refinement before application to this model. 相似文献
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Kosuke Abe Nobuyuki Higashimori Masayoshi Kubo Hiroshi Fujiwara & Yuusuke Iso 《advances in applied mathematics and mechanics.》2014,6(5):693-698
The Courant-Friedrichs-Lewy condition (The CFL condition) is
appeared in the analysis of the finite difference method
applied to linear hyperbolic partial differential equations.
We give a remark on the CFL condition from a view point of
stability, and we give some numerical experiments
which show instability of numerical solutions even under the
CFL condition. We give a mathematical model for rounding errors
in order to explain the instability. 相似文献
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《Waves in Random and Complex Media》2013,23(3):515-528
The propagation of in-plane (P-SV) waves in a symmetrically three-layered thick plate with a periodic array of interface cracks is investigated. The exact dispersion relation is derived based on an integral equation approach and Floquet's theorem. The interface cracks can be a model for interface damage, but a much simpler model is a recently developed spring boundary condition. This boundary condition is used for the thick plate and also in the derivation of plate equations with the help of power series expansions in the thickness coordinate. For low frequencies (cracks small compared to the wavelength) the three approaches give more or less coinciding dispersion curves, and this is a confirmation that the spring boundary condition is a reasonable approximation at low frequencies. 相似文献
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In this article, the analysis of Tsallis holographic dark energy(which turns into holographic dark energy for a particular choice of positive non-additivity parameter δ) in modified f(T, B) gravity with the validity of thermodynamics and energy conditions for a homogeneous and isotropic FLRW Universe has been studied. The enlightenment of the field equation towards f(T,B)=αT~m+βB~n, made possible by the fact that the model is purely accelerating,corresponds to q=-0.54(Mamon and Das 2017 Eur. Phys.J.C 77 49). The generalized second law of thermodynamics is valid not only for the same temperature inside the horizon, but also for the apparent horizon for a change in temperature. The essential inspiration driving this article is to exhibit the applicability that the holographic dark energy achieved from standard Tsallis holographic dark energy and the components acquired from f(T, B) gravity are identical for the specific bounty of constants. The analysis of energy conditions confirms that the weak energy condition and the null energy condition are fulfilled throughout the expansion, while violation of the strong energy condition validates the accelerated expansion of the Universe.With the expansion, the model becomes a quintessence dominated model. The dominant energy condition is not observed initially when the model is filled with genuine baryonic matter,whereas it appears when the model is in the quintessence dominated era. 相似文献
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The conjecture that supersymmetry breaking implies superconductivity is supported by the analysis of a class of supersymmetric non-relativistic models involving only fermions. Here the investigation is extened to a non-relativistic model involving both fermions and bosons, which in a sense is the non-relativistic version of the Wess-Zumino model. A sufficient condition is established for the validity of the conjecture. This condition can be possibly violated at most in a two-dimensional subspace of the three-dimensional space of the coupling constants. 相似文献