共查询到20条相似文献,搜索用时 15 毫秒
1.
This paper investigates the collision between two nonlinear waves with different propagation directions in two-dimensional dust crystals. Using the extended Poincaré--Lighthill-Kuo perturbation method, two Korteweg--de Vries equations for nonlinear waves in both the ξ and eta directions are obtained, respectively, and the analytical phase shifts and trajectories after the collision of two nonlinear waves are derived. Finally, the effects of parameters of the lattice constant a, the arbitrary constant u0η, the forces f(r), and the colliding angle θ on the phase shifts of both colliding nonlinear waves are examined. 相似文献
2.
The kink-soliton and antikink-soliton in quasi-one-dimensional nonlinear monoatomic lattice 总被引:1,自引:0,他引:1
XU Quan & TIAN Qiang . Scientific Technological Office Daqing Teacher College Daqing China . Department of Physics Beijing Normal University Beijing China 《中国科学G辑(英文版)》2005,48(2)
1 Introduction During recent decades great progress has been made in the soliton formation and its application in one-dimensional (1D) system. The interest in the soliton modes has been intensified due to their observation in the energy propagating along bio- logical molecule chain. The new achievement in studying the topological soliton in polyacetylene molecule chain and the phenomena of transformation with the action of electric field are continuously reported[1]. The electric field domain… 相似文献
3.
Localized self-trapping in two-dimensional molecular lattice with interaction between Wannier-Mott excitons and phonon lattice 下载免费PDF全文
We investigate the interactions of lattice phonons with Wannier-Mott exciton, the exciton that has a large radius in two-dimensional molecular lattice, by the method of continuum limit approximation, and obtain that the self-trapping can also appear in two-dimensional molecular lattice with a harmonic and nonlinear potential. The exciton effect on molecular lattice does not distort the molecular lattice but only makes it localized and the localization can also react, again through phonon coupling, to trap the energy and prevents its dispersion. 相似文献
4.
Localized self-trapping in the two-dimensional discrete molecular lattice with the interaction between Frenkel excitons and phonons 下载免费PDF全文
We investigate the interactions of lattice phonons with Frenkel
exciton, which has a small radius in a two-dimensional discrete
molecular lattice, by the virtue of the quasi-discreteness
approximation and the method of multiple-scale, and obtain that the
self-trapping can also appear in the two-dimensional discrete molecular
lattice with harmonic and nonlinear potential. The excitons' effect
on the molecular lattice does not distort it but only
causes it to localize which enables it to react again through phonon
coupling to trap the energy and prevent its dispersion. 相似文献
5.
通过使用推广的 Poincar-Lighthill-Kuo 摄动方法,研究了二维热离子等离子体中两个沿不同方向传播的离子声孤波的相互作用,得到了两个分别描述沿ξ和η方向传播的孤波的KdV方程以及两个孤波以任意夹角碰撞后的相移和轨道.同时还研究了离子温度比σ、热容比γ和碰撞夹角α对孤波相移的影响.研究表明,这些参量可以明显地改变孤波的相移,且在该系统中存在压缩型孤波.
关键词:
热离子等离子体
离子声孤波
Poincar-Lighthill-Kuo方法
相移 相似文献
6.
7.
Two-dimensional discrete breathers in a two-dimensional Morse lattice with on-site harmonic potentials are investigated. Under the harmonic approximation, the linear dispersion relations for the triangular and the square lattices are discussed. The existence of discrete breathers in a two-dimensional Morse lattice with on-site harmonic potentials is proved by using local inharmonic approximation and the numerical method. The localization and amplitude of two-dimensional discrete breathers correlate closely to the Morse parameter a and the on-site parameter κ. 相似文献
8.
We study analytically and numerically the effect of nonlinearity on transmission of waves through a random medium. We introduce and analyze quantities associated with the scattering problem that clarify the lack of uniqueness due to the nonlinearity as well as the localization of waves due to the random inhomogeneities. We show that nonlinearity tends to delocalize the waves and that for very large scattering regions the average transmitted energy is small. 相似文献
9.
Morikazu Toda 《Proceedings of the Japan Academy. Series B, Physical and biological sciences》2004,80(10):445
In this article a brief review of the theory of one-dimensional nonlinear lattice is presented. Special attension is paid for the lattice of particles with exponential interaction between nearest neighbors (the Toda lattice). The historical exposition of findings of the model system, basic equations of motion, special solutions, and the general method of solutions are given as chronologically as possible. Some reference to the Korteweg-de Vries equation is also given. The article consists of three parts. Firstly, the idea of dual system is presented. It is shown that the roles of masses and springs of a harmonic linear chain can be exchanged under certain condition without changing the eigenfrequencies. Secondly, the idea is applied to the anharmonic lattice and an integrable lattice with exponential interaction force between adjacent particles is obtained. Special solutions to the equations of motion and general method of solution are shown. In the last part, some studies on the Yang-Yang’s thermodynamic formalism is given. 相似文献
10.
Experimental realization of two-dimensional single-layer ultracold gases of 87Rb in an accordion lattice 下载免费PDF全文
Liangwei Wang 《中国物理 B》2022,31(10):103401-103401
We experimentally realize two-dimensional (2D) single-layer ultracold gases of 87Rb by dynamically tuning the periodicity of a standing wave, known as accordion lattice. In order to load 87Rb Bose—Einstein condensate into single dark fringe node of the blue detuning optical lattice, we reduce the lattice periodicity from 26.7 μ to 3.5 μ with the help of an acousto-optic deflector (AOD) to compress the three-dimensional BEC adiabatically into a flat and uniform quasi-2D single-layer. We describe the experimental procedure of the atoms loading into the accordion lattice in detail and present the characteristics of the quasi-2D ultracold gases. This setup provides an important platform for studying in- and out-of equilibrium physics, phase transition and 2D topological matter. 相似文献
11.
设计了一种棋盘格子复式晶格的二维光子晶体:在二维正方形格子中,把截面为正方形的柱子旋转45°,同时在每个原胞中心引入一个圆形截面的柱子构成的光子晶体结构. 用平面波展开计算棋盘格子复式晶格的完全光子带隙,结果表明:棋盘格子复式晶格的完全光子带隙的Δω/ω比值几乎是普通棋盘格子的5倍,完全光子带隙的个数也增加. 与其他复式结构相比较,发现其最佳的Δω/ω比值是一类粗锐复合结构光子晶体的2.1倍.
关键词:
二维光子晶体
复式晶格
完全光子带隙 相似文献
12.
13.
利用含时变分法研究了二维光晶格中准二维玻色-爱因斯坦凝聚中的调制不稳定性. 在平均场近似下, 由准二维Gross-Pitaevskii方程出发, 利用变分法给出了调制波振幅和相位所满足的时间演化方程, 通过求解时间演化方程和能量分析法给出了发生调制不稳定性的条件, 决定于平面波振幅, 晶格强度, 调制波的波矢量和原子之间的两体相互作用. 相似文献
14.
二维磁性材料是近几年新兴的研究领域,该材料在开发自旋电子器件等领域具备良好的应用潜能.为了了解二维磁性材料的磁性质,明确体系内各近邻磁性原子间的磁相互作用非常重要.第一性原理为各近邻磁交换参数的计算奠定了基础.目前各近邻参数的第一性原理计算常用的是能量映射法,但这种方法存在一定的缺陷.本文通过广义布洛赫条件推导了3种常见二维磁性结构的海森伯作用与Dzyaloshinskii-Moriya (DM)相互作用的自旋螺旋色散关系,这3种结构为四方结构,元胞包含一个磁性原子的六角结构,元胞包含两个磁性原子的六角结构.为了将本文推导的自旋螺旋色散关系应用于实际,我们通过第一性原理计算了一些材料的海森伯和DM作用的交换参数,这些材料分别是MnB,VSe2,MnSTe,Cr2I3Cl3.其中,MnSTe和Cr2I3Cl3都属于二维Janus材料,磁性原子层的上下层对称性破缺,整个体系存在DM相互作用. 相似文献
15.
In this paper we study the existence and stability of two-dimensional discrete gap
breathers in a two-dimensional diatomic face-centered square lattice
consisting of alternating light and heavy atoms, with on-site
potential and coupling potential. This study is focused on
two-dimensional breathers with their frequency in the gap that
separates the acoustic and optical bands of the phonon spectrum. We
demonstrate the possibility of the existence of two-dimensional gap
breathers by using a numerical method. Six types of two-dimensional
gap breathers are obtained, i.e., symmetric, mirror-symmetric and
asymmetric, whether the center of the breather is on a light or a
heavy atom. The difference between one-dimensional discrete gap
breathers and two-dimensional discrete gap breathers is also
discussed. We use Aubry's theory to analyze the stability of
discrete gap breathers in the two-dimensional diatomic face-centered
square lattice. 相似文献
16.
The dynamics of the nonlinear excitations in a two-dimensional (2D) φ4-diatomic lattice, with nonlinear on-site electron-phonon coupling at the polarizable ion site has been presented, without
considering the self consistent phonon approximation. One of the major results obtained from our calculations is in the understanding
of continuous structural phase transition, where we have obtained the minimum in soft mode frequency at a soft mode temperatureT
s (>T
c), not at critical temperatureT
c. This occurs due to the anisotropy of such 2D systems. 相似文献
17.
The lattice Boltzmann phononic lattice solid 总被引:6,自引:0,他引:6
Peter Mora 《Journal of statistical physics》1992,68(3-4):591-609
I present a Boltzmann lattice gas-like approach for modeling compressional waves in an inhomogeneous medium as a first step toward developing a method to simulate seismic waves in complex solids. The method is based on modeling particles in a discrete lattice with wavelike characteristics of partial reflection and transmission when passing between links with different properties as well as phononlike interactions (i.e., collisions), with particle speed dependent on link properties. In the macroscopic limit, this approach theoretically yields compressional waves in an inhomogeneous acoustic medium. Numerical experiments verify the method and demonstrate its convergence properties. The lattice Boltzmann phononic lattice solid could be used to study how seismic wave anisotropy and attenuation are related to microfractures, the complex geometry of rock matrices, and their couplings to pore fluids. However, additional particles related to the two transverse phonons must be incorporated to correctly simulate wave phenomena in solids. 相似文献
18.
19.
In this paper, the internal field distribution of higher order MDRs of water droplets is calculated and the result shows that the higher order MDRs should dominate the nonlinear couple process. Furthermore, the phase matching required for four-wave mixing (FWM) process in the droplet is interpreted as the concept of angular momentum conservation. The slight mismatch in angular momentum leads to significant improvement of phase matching than that in optical cell. 相似文献
20.
By introducing the traffic anticipation effect in the real world into the original lattice hydrodynamic model, we present a new anticipation effect lattice hydrodynamic (AELH) model, and obtain the linear stability condition of the model by applying the linear stability theory. Through nonlinear analysis, we derive the Burgers equation and Korteweg-de Vries (KdV) equation, to describe the propagating behaviour of traffic density waves in the stable and the metastable regions, respectively. The good agreement between simulation results and analytical results shows that the stability of traffic flow can be enhanced when the anticipation effect is considered. 相似文献