共查询到16条相似文献,搜索用时 109 毫秒
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对具有在位势且含杂质的一维双原子链的晶格振动方程组进行求解,得到了局域振动的解析解, 给出了在位势对局域振动影响的基本特征,并简要讨论了局域模的存在形式. 相似文献
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通过数值求解具有在位势的一维双原子链晶格振动的运动方程组,给出了具有不同大小在位势的长声学波振动模图像,直观展示出在位势使原胞中两种原子的振动位移不同,并且随在位势的增大,振动位移之差显著增大. 相似文献
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具有在位势的一维双原子链晶格振动的色散关系 总被引:1,自引:1,他引:0
在简谐近似下,求解具有在位势的一维双原子链晶格振动运动方程,得到了具有在位势的晶格振动的色散关系.在位势使色散关系声频支在布里渊区中心的振动频率不再为零,并且随在位势的增大而增大.对于原子之间相互作用势不随在位势大小变化的情况下,晶格振动的色散关系的频隙随在位势的增大而变宽.讨论了原子链由只有在位势的不连续极限(AC极限),通过在位势逐渐减弱而原子间相互作用势逐渐增强,最后演变到只有原子间相互作用势的原子链的情况.随着在位势减弱和相互作用势增强,色散关系的频隙由AC极限的孤立轻、重原子简谐振动频率之差逐渐变化到通常的无在位势的色散关系频隙. 相似文献
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考虑原子间次近邻相互作用,讨论了具有在位势的一维双原子链中杂质引起的局域振动,得到次近邻互作用力、在位势共同作用下局域模的存在条件及振动的基本特征. 相似文献
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采用线性组合算符及幺正变换方法研究了磁场对量子阱中弱耦合束缚极化子的性质的影响。导出了量子阱中束缚极化子的基态能量与振动频率、库仑束缚势、磁场和阱宽之间的变化关系。同时也讨论了振动频率与库仑束缚势、磁场之间的变化关系。通过数值计算结果表明:量子阱中束缚极化子的基态能量因振动频率、库仑束缚势、磁场和阱宽的不同而不同,它随振动频率和磁场的增加而增大,随库仑束缚势和阱宽的增大而减小。量子阱中束缚磁极化子的基态能量与振动频率无关,随库仑束缚势和阱宽的增大而减小,随磁场的增大而增大。 相似文献
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T. Jeong 《Solid State Communications》2006,138(8):386-389
The electronic band structure of CeAgSb2 has been calculated using the self-consistent full potential nonorthogonal local orbital minimum basis scheme based on the density functional theory. We investigated the electronic structure with the spin-orbit interaction and on-site Coulomb potential for the Ce-derived 4f orbitals to obtain the correct ground state of CeAgSb2. 相似文献
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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
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Thermal transport in the FPU model with FK on-site potential is studied by using fourth-order Runge-Kutta algorithm. The heat flux, local temperature profile, and heat conductivity are simulated and analyzed. It is found that temperature gradient scales behave as N-1 linearly. The divergence of heatconductivity κ with system size N is in term of κ∝ N^α with α=0.44. It is shown that thermal transport is mainly dependent on the FPU nonlinear and the FK interactions. 相似文献
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The role of on-site potential disorder on phonon transmission and thermal conductance of one-dimensional system is investigated. We found that the on-site potential disorder can lead to the localization of phonons, and has great effect on the phonon transmission and thermal conductance of the system. As on-site potential disorder W increases, the transmission coefficients decrease, and approach zero at the band edges. Corresponding, the thermal conductance decreases drastically, and the curves for thermal conductance exhibit a series of steps and plateaus. Meanwhile, when the on-site potential disorder W is strong enough, the thermal conductance decreases dramatically with the increase of system size N. We also found that the efficiency of reducing thermal conductance by increasing the on-site potential disorder strength is much better than that by increasing the on-site potential?s amplitude. 相似文献
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Assessment of Timoshenko Beam Models for Vibrational Behavior of Single-Walled Carbon Nanotubes Using Molecular Dynamics 下载免费PDF全文
Y. Y. Zhang C. M. Wang & V. B. C. Tan 《advances in applied mathematics and mechanics.》2009,1(1):89-106
In this paper, we study the flexural vibration behavior of
single-walled carbon nanotubes (SWCNTs) for the assessment of
Timoshenko beam models. Extensive molecular dynamics (MD)
simulations based on second-generation reactive empirical bond-order
(REBO) potential and Timoshenko beam modeling are performed to
determine the vibration frequencies for SWCNTs with various
length-to-diameter ratios, boundary conditions, chiral angles and
initial strain. The effectiveness of the local and nonlocal
Timoshenko beam models in the vibration analysis is assessed using
the vibration frequencies of MD simulations as the benchmark. It is
shown herein that the Timoshenko beam models with properly chosen
parameters are applicable for the vibration analysis of SWCNTs. The
simulation results show that the fundamental frequencies are
independent of the chiral angles, but the chirality has an
appreciable effect on higher vibration frequencies. The SWCNTs is
very sensitive to the initial strain even if the strain is extremely
small. 相似文献