On the basis of complex frequency‐shifted perfectly matched layer (CFS‐PML) formulation, an implementation of the higher‐order PML is proposed to terminate unbounded finite‐difference time domain (FDTD) computational domain. By incorporating the Crank‐Nicolson Douglas‐Gunn algorithm and the bilinear transform method, the proposed scheme can not only maintain the unconditional stability of the CN‐FDTD algorithm in terms of reducing computational time but also take advantage of the higher‐order PML in terms of improving absorbing performance. Numerical examples are provided to demonstrate the performance of the proposal in the homogenous free space and half‐space soil vacuum problems, respectively. It is demonstrated that the proposed unconditionally stable higher‐order CFS‐PML can not only efficiently absorb low‐frequency propagation waves, low‐frequency evanescent waves, and late‐time reflections but also overcome Courant‐Friedrich‐Levy limit.

中文翻译：

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隐式CNDG-FDTD算法的高阶完美匹配层

在复杂频移完美匹配层（CFS-PML）公式的基础上，提出了一种更高阶PML的实现方式，以终止无界有限差分时域（FDTD）计算域。通过结合Crank-Nicolson Douglas-Gunn算法和双线性变换方法，所提出的方案不仅可以在减少计算时间方面保持CN-FDTD算法的无条件稳定性，而且可以利用较高阶PML的优势。吸收性能的改善。数值例子说明了该方案在均质自由空间和半空间土壤真空问题中的性能。结果表明，提出的无条件稳定的高阶CFS-PML不仅可以有效地吸收低频传播波，