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1.
The effects of cubic potentials on discrete breathers in a mixed Klein-Gordon /Fermi-Pasta-Ulam chain 下载免费PDF全文
Nonlinearity has a crucial impact on the symmetry properties of dynamical
systems. This paper studies a one-dimensional mixed Klein--Gordon/Fermi--Pasta--Ulam diatomic
chain using the expanded rotating plane-wave approximation and numerical
calculations to determine the effect of cubic potentials on the symmetry
properties of discrete breathers in this system. The results will be very
useful to researchers in the field of numerical calculations on
discrete breathers. 相似文献
2.
Periodic, Quasiperiodic and Chaotic Discrete Breathers in a Parametrical Driven Two-Dimensional Discrete Klein-Gordon Lattice 下载免费PDF全文
We study a two-dimensional lattice of anharmonic oscillators with only quartic nearest-neighbor interactions, in which discrete breathers can be explicitly constructed by an exact separation of their time and space dependence. DBs can stably exist in the two-dimensional Klein-Gordon lattice with hard on-site potential. When a parametric driving term is introduced in the factor multiplying the harmonic part of the on-site potential of the system, we can obtain the stable quasiperiodic discrete breathers and chaotic discrete breathers by changing the amplitude of the driver. 相似文献
3.
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
4.
Binding energies of excitons in GaAs films on AlxGa1-xAs substrates are studied theoretically with the fractional-dimensional approach. In this approach, the real anisotropic “exciton+film” semiconductor system is mapped into an effective fractional-dimensional isotropic space. For different aluminum concentrations and substrate thicknesses, the exciton binding energies are obtained as a function of the film thickness. The numerical results show that, for different aluminum concentrations and substrate thicknesses, the exciton binding energies in GaAs films on AlxGa1-xAs substrates all exhibit their maxima with increasing film thickness. It is also shown that the binding energies of heavy-hole and light-hole excitons both have their maxima with increasing film thickness. 相似文献
5.
奥克托金(HMX) 在温度作用下, 会发生热膨胀、 相转变、 热分解等物理、 化学变化, 导致在材料内部产生大量缺陷, 进而会对其宏观性能造成明显影响. 为了深入了解热损伤HMX内部的缺陷演化, 本文采用X射线小角散射和原子力显微技术研究了热损伤HMX的内部缺陷. 结果发现HMX在180 °C相变过程中散射曲线有明显的变化, 颗粒内部生成了大量10nm左右的孔洞, 随着加载时间延长, 其尺寸增大到25nm, 数量明显降低. 当HMX在190 °C、 200 °C保温5h时, 由于HMX热分解内部有新缺陷生成, 小角散射发现其尺寸约为5至8nm, 随着加载温度升高, 其数量增加. 相似文献
6.
用能带理论分析一维超晶格电子在直流外场作用下的阻尼运动,对Bloch振荡和负微分电导现象给出清楚的物理图象,并通过数值解得到有阻尼时振荡频率随外场增加而趋近于Bloch频率的一般规律。 相似文献
7.
Existence and Stability of Compact-Like Discrete Breather in Discrete One-Dimensional Monatomic Chains 下载免费PDF全文
Compact-like discrete breathers in discrete one-dimensional monatomic chains are investigated by discussing a generalized discrete one-dimensional monatomic model. It is proven that compact-like discrete breathers exist not only in soft Ф^4 potential but also in hard Ф^4 potential and K4 chains. The measurements of compact-like discrete breathers' core in soft and hard Ф^4 potential are determined by coupling parameter K4, while the measurements of compact-like discrete breathers' core in K4 chains are not related to coupling parameter K4. The stabilities of compact-like discrete breathers correlate closely to coupling parameter K4 and the boundary condition of lattice. 相似文献
8.
本文采用分数维方法, 在讨论Al0.3Ga0.7As衬底上GaAs薄膜的分数维基础上, 计算了GaAs薄膜中的极化子结合能和有效质量. 随着薄膜厚度的增加, 极化子结合能和质量变化单调地减小. 当薄膜厚度Lw<70 Å并且衬底厚度Lb<200 Å时, 衬底厚度的变化对薄膜中极化子的结合能和质量变化的影响比较显著, 随着衬底厚度的增加, 薄膜中极化子的结合能和质量变化逐渐变大; 当薄膜厚度Lw>70 Å或者衬底厚度Lb>200 Å时, 衬底厚度的变化对薄膜中极化子的结合能和质量变化的影响不显著. 研究结果为GaAs薄膜电子和光电子器件的研究和应用提供参考.
关键词:
分数维方法
GaAs薄膜
极化子
低维异质结构 相似文献
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