Relaxation method and TCLE method of linear response in terms of thermo-field dynamics
Relaxation method and TCLE method of linear response in terms of thermo-field dynamics
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热场动力学线性响应的弛豫法和TCLE法
DOI：
10.1016/j.physa.2007.11.016
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发表时间：
2008
影响因子：
3.3
通讯作者：
M. Saeki
中科院分区：
文献类型：
--
作者：
M. Saeki
通过引入热场动力学(TFD)中的重整化HAT算符，用松弛方法和TCLE方法导出了线性响应的动力极化率的一般公式。在前一种方法中，Kubo公式是在没有外驱动场的情况下计算的，而在后一种方法中，导纳是由有外驱动项的无时间卷积方程直接计算的。分析了这两种方法之间的关系，并用TFD检验了这两种方法的涨落耗散定理。将TCLE方法应用于一个相互作用的自旋系统，导出了该系统的横向磁化率公式。得到了自旋-自旋相互作用的一次幂函数形式的S=1/2自旋相互作用体系的横向磁化率。
The general formulae of the dynamic susceptibility are derived using the relaxation method and the TCLE method for the linear response by introducing the renormalized hat-operator in terms of thermo-field dynamics (TFD). In the former method, the Kubo formula is calculated for systems with no external driving fields, while in the latter method the admittance is directly calculated from time-convolutionless equations with external driving terms. The relation between the two methods is analytically investigated, and also the fluctuation–dissipation theorem is examined for the two methods in terms of TFD. The TCLE method is applied to an interacting spin system, and a formula of the transverse magnetic susceptibility is derived for such a system. The transverse magnetic susceptibility of an interacting spin system with S=1/2 spins is obtained up to the first order in powers of the spin–spin interaction.