排序方式: 共有18条查询结果,搜索用时 30 毫秒
1.
近年来国内外对多原子极性晶体中磁极化子性质的研究十分活跃,Zorkani等采用变分法计算了束缚磁极化子的基态能量,Kandemir等采用束缚朗道态讨论了二维大磁极化子的基态和第一激发态能量,国内一些学者采用微扰法和新颖算符法讨论了多原子极性晶体中表面和体磁极化子的性质。采用线性组合算符和幺正变换,研究磁场中多原子半无限极性晶体中电子和光学声子弱耦合相互作用所产生的极化子的第一激发态能量及平均声子数。结果表明:当电子无限接近晶体表面时,磁极化子的基态能量仅为Landau能量;第一激发态能量为Landau基态能量的2倍;平均声子数等于各支与电子耦合的体光学声子数和表面光学声子数之和。而当电子处于晶体深处时,磁极化子的基态能量却为Landau基态能量与各支体光学声子以及表面光学声子分别耦合的能量之和;第一激发态能量仍为Landau基态能量的2倍;平均声子数等于各支与电子耦合的体光学声子数和与所处深度有关的各支体光学声子数之和,而与各支表面光学声子无关。 相似文献
2.
We generalize the Wu-Yang strong-coupling theory to solve
analytically periodically driven two-level systems in the weak-coupling and
low-frequency regimes for single- and multi-period periodic driving of
continuous-wave-type and pulse-type including ultrashort pulses of a few
cycles. We also derive a general formula of the AC Stark shift suitable for such diverse situations. 相似文献
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B. N. Shalaev 《Theoretical and Mathematical Physics》2002,131(2):621-628
We show that the exact beta function of the two-dimensional g4 theory possesses two dual symmetries. These are the Kramers–Wannier symmetry d(g) and the strong–weak-coupling symmetry, or the S-duality f(g), connecting the strong- and weak-coupling domains lying above and below the fixed point g
*. We obtain explicit representations for the functions d(g) and f(g). The S-duality transformation f(g) allows using the high-temperature expansions to approximate the contributions of the higher-order Feynman diagrams. From the mathematical standpoint, the proposed scheme is highly unstable. Nevertheless, the approximate values of the renormalized coupling constant g
* obtained from the duality equations agree well with the available numerical results. 相似文献
5.
基于对体光栅衍射效率的计算分析,本文直接地、精细地讨论了体光栅的功率守恒问题.结果指出:弱耦合前提假定下的双波耦合波二阶理论,不能严格地满足能量平衡准则. 相似文献
6.
采用Huybrechts线性组合算符和幺正变换方法研究了抛物量子点中的强、弱耦合极化子的激发态性质。分别导出强、弱耦合情况下,抛物量子点中的极化子的第一内部激发态能量、激发能量、共振频率与量子点的有效受限长度和电子-声子耦合强度的关系。数值计算结果表明,量子点中弱耦合和强耦合极化子的内部激发态能量、激发能量和共振频率都随量子点的有效受限长度的减小而迅速增大。弱耦合极化子的第一内部激发态能量随电子-声子耦合强度的增加而减少;而强耦合极化子的振动频率随量子点的有效受限长度的减小而迅速增加。弱耦合极化子的第一内部激发态能量、激发能量和共振频率随电子-声子耦合强度的增加而减小。 相似文献
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利用直接标度分析方法研究一个含有广义守恒律生长方程的标度奇异性,得到强弱耦合区域的奇异标度指数.作为其特殊情况,这个方程包含Kardar-Parisi-Zhang(KPZ)方程、 Sun-Guo-Grant(SGG)方程以及分子束外延(MBE)生长方程,并能对其进行统一的研究.研究发现, KPZ方程和SGG方程,无论在弱耦合还是在强耦合区域内都遵从自仿射Family -Vicsek正常标度规律;而MBE 方程在弱耦合区域内服从正常标度,在强耦合区域内能呈现内禀奇异标度行为.这里所得到生长方程的奇异标度性质与利用重正化群理论、数值模拟以及实验相符很好.
关键词:
标度奇异性
强耦合
弱耦合 相似文献
9.
Starting with the Hamiltonian for a linear harmonic chain of 2N particles of massm and one of massM, we have carried out numerical calculations for the momentum autocorrelation function of the mass defect particle for chains with finite numberN of mass points and for nonzero values of the mass ratio=m/M. These results have been compared with the well-known exponential relaxation of the momentum autocorrelation function which is found to be the rigorous result when passing to the thermodynamic and weak-coupling limit. In these limits, the dynamics of the mass defect particle is exactly described by a Fokker-Planck equation, i.e., a stochastic equation of motion. We have shown that, to an excellent approximation, an exponential relaxation of the momentum autocorrelation function is obtained for mass ratios as high as=0.1 and for chains with only 50 particles. Thus, for the harmonic chain considered here, the stochastic equations of motion can be applied to a very good approximation far outside the usually imposed thermodynamic and weak-coupling limits.Supported in part by the Advanced Research Projects Agency of the Department of Defense as monitored by the U.S. Office of Naval Research under Contract N00014-69-A-0200-6018 and by the National Science Foundation under Grant GP28257X. 相似文献
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ZHOU Qing-Ping FANG Mao-Fa 《理论物理通讯》2008,49(4):1025-1028
We present an approximate analytical solution to periodically driven two-level system in the weak-coupling regime. The analytical solution is in good agreement with the exact numerical
solution in resonance and near resonance cases when Ω≤0.3ωa with Ω and ωa denoting the Rabi and transition frequencies respectively. 相似文献