Zero and First Sound in Normal Fermi Systems
Zero and First Sound in Normal Fermi Systems
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DOI：
10.1007/s10909-009-0043-4
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发表时间：
2009-10
影响因子：
2
通讯作者：
S. Watabe;A. Osawa;T. Nikuni
中科院分区：
文献类型：
--
作者：
S. Watabe;A. Osawa;T. Nikuni
利用矩量法研究了正常费米系统线性化玻尔兹曼方程的通解。特别是，我们研究的声速和阻尼率作为温度和耦合常数的函数。在无碰撞和流体动力学状态的极端极限下，由矩方程得到的声模本征频率再现了零声和第一声的著名结果。此外，矩量法可以描述在有限温度下这些极限之间的交叉。力矩方程的解也涉及热扩散模式。从这些方程的解，我们讨论了相应的激发谱的粒子-空穴连续以及集体激发。我们还讨论了弱耦合情况下的集体模。
On the basis of a moment method, general solutions of a linearized Boltzmann equation for a normal Fermi system are investigated. In particular, we study the sound velocities and damping rates as functions of the temperature and the coupling constant. In the extreme limits of collisionless and hydrodynamic regimes, eigenfrequency of sound mode obtained from the moment equations reproduces the well-known results of zero sound and first sound. In addition, the moment method can describe crossover between those extreme limits at finite temperatures. Solutions of the moment equations also involve a thermal diffusion mode. From solutions of these equations, we discuss excitation spectra corresponding to the particle-hole continuum as well as collective excitations. We also discuss a collective mode in a weak coupling case.