The recently discovered two-dimensional (2D) layered semiconductor $\mathrm{Mo}{\mathrm{Si}}_2{\mathrm{N}}_4$ has aroused great interest due to its unique 2D material characteristics. In this study, we found that differences in the structural details for $\mathrm{Mo}{\mathrm{Si}}_2{\mathrm{N}}_4$ may lead to differences in the intensity of second harmonic generation (SHG) and its response to strain. Accordingly, SHG can be used as a simple technique to identify the structural details of this system. We further calculated the SHG effects of $\mathrm{Mo}{\mathrm{Si}}_2{\mathrm{N}}_4$ derivatives and investigated their strain-regulation mechanism, especially including the anomalous SHG responses under strain for $\mathrm{Mo}{\mathrm{Si}}_2{\mathrm{P}}_4$ and $\mathrm{Mo}{\mathrm{Ge}}_2{\mathrm{P}}_4$, differing from other known 2D materials. The studies may have forward-looking significance for the research of nonlinear optics and optoelectronics in this novel 2D material system.

中文翻译：

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MoSi2N4型层的二次谐波产生

最近发现的二维（2D）分层半导体 $莫{硅}_{\mathrm{2个}}{\mathrm{ñ}}_4$由于其独特的2D材质特性，引起了极大的兴趣。在这项研究中，我们发现$莫{硅}_{\mathrm{2个}}{\mathrm{ñ}}_4$可能会导致二次谐波产生（SHG）的强度及其对应变的响应有所不同。因此，SHG可以用作识别该系统结构细节的简单技术。我们进一步计算了SHG的影响$莫{硅}_{\mathrm{2个}}{\mathrm{ñ}}_4$ 衍生物并研究了它们的应变调节机制，特别是包括应变下的SHG异常反应。 $莫{硅}_{\mathrm{2个}}{\mathrm{P}}_4$ 和 $莫{\mathrm{通用电器}}_{\mathrm{2个}}{\mathrm{P}}_4$，与其他已知的2D材料不同。这些研究对于这种新颖的2D材料系统中的非线性光学和光电子学研究可能具有前瞻性意义。