There is a paucity of previous related studies exploring hexagonal MgZn₂ in high-pressure environments. This study systematically analyzes the mechanical behavior of MgZn₂ hexagonal alloys under high-pressure conditions using first principle calculations, bridging the gap in research in this area in the field. The results reveal that, with increasing pressure, the crystallite spacing ($a/a_0,c/c_0$) and ratio of volumes ($V/V_0$) decrease significantly, indicating the structural condensation of the material under high pressure. Elastic constant analysis showed a notable enhancement in all constants, except for $C_{13}$. Among them, $C_{11}$ increased from 87.399 GPa to 311.45 GPa, and $C_{33}$ increased from 135.279 GPa to 341.739 GPa, showing a faster growth rate, suggesting improved tensile strength in the material along the tensile direction. Mechanical stability assessments confirmed that the alloy remains stable over the 0 to 30 GPa pressure range. Further material characterization indicated that Poisson’s ratio remained above 0.26 at pressures from 0 to 30 GPa, suggesting excellent ductility and agreeing with the ratio of the shear modulus to the bulk modulus. As the pressure increases, both the hardness and sound velocity of MgZn₂ increase, while the degree of anisotropy decreases. The present work gives important insights on the mechanical behavior of MgZn₂ under high pressure, contributing to its application and property optimization.

The geometric structures of an NH radical in different external electric fields are optimized by using the density functional B3P86/cc-PV5Z method, and the bond lengths, dipole moments, vibration frequencies and IR spectrum are obtained. The potential energy curves are gained by the CCSD (T) method with the same basis set. These results indicate that the physical property parameters and potential energy curves may change with the external electric field, especially in the reverse direction electric field. The potential energy function of zero field is fitted by the Morse potential, and the fitting parameters are in good accordance with the experimental data. The potential energy functions of different external electric fields are fitted adopting the constructed potential model. The fitted critical dissociation electric parameters are shown to be consistent with the numerical calculation, and the relative errors are only 0.27% and 6.61%, hence the constructed model is reliable and accurate. The present results provide an important reference for further study of the molecular spectrum, dynamics and molecular cooling with Stark effect.

采用内收缩多参考组态相互作用(ic-MRCI)方法和相对论有效芯赝势基(aug-cc-pV5Z-PP),优化计算一溴化锶(⁸⁸Sr⁷⁹Br)分子14个低激发电子态的电子结构和单点能.为了获得更加精确的光谱参数,引入Davidson、核价电子相关和相对论效应修正单点能,根据优化修正得到的单点能分析获得了最低5个束缚态的势能曲线和偶极矩.利用LEVEL8.0程序拟合修正的势能曲线,得到各束缚态的光谱常数、分子常数和振动能级等光谱性质参数.对比发现本文计算的结果与实验值吻合较好,最后给出了跃迁性质参数Franck-Condon因子和辐射寿命.这些光谱特性参数为进一步实验测量和构建分子激光冷却方案提供理论支持.

在无自旋轨道耦合的s波超导表面，磁通与吸附的磁性原子形成的反铁磁序的结合能够诱导高阶拓扑超导.然而，实际磁晶格中受多种因素影响，磁序往往偏离理想的反铁磁构型，产生不同类型的畸变.为此，本文在反铁磁模型中引入铁磁序与螺旋磁序作为畸变因素，系统探究该模型下的高阶拓扑超导性质，并深入剖析高阶拓扑态形成的物理根源.研究结果表明，反铁磁序是实现高阶拓扑超导的必要前提；铁磁序虽会重整能带结构，但不会破坏高阶拓扑能隙.相较之下，螺旋成分的加入会使能带发生倾斜畸变，一旦相邻磁矩间的夹角增大至临界值，能隙便完全闭合，拓扑态随之消失.

Sr35Cl is a candidate system for laser cooling. The spectrum and transition characteristics are very important for constructing laser cooling schemes. In this paper, the spectral properties are analyzed by using the Davidson's modified internal contraction multi-reference interaction (ic-MRCI + Q) method, in combination with the relativistic effective core pseudopotential group (aug-cc-pV5Z-PP) as the base group for the calculation of the Sr atom and the related consistent quintile aug-cc-pV5Z as the Cl atom. The potential energy curves and dipole moments of 14 low excited electron states of Sr35Cl molecule are optimized. In order to obtain more accurate spectral parameters, nuclear valence electron correlation and relativistic effect correction are introduced into the calculation. Using the LEVEL 8.0 program to fit the modified potential energy curves of 5 bound states, the spectral properties such as spectral constants, vibration energy levels, and molecular constants of the corresponding electron states are obtained. The results show that there is a double potential well in \begin{document}${\rm B}^2 \Sigma^+$\end{document} state and the cross phenomena are avoided in \begin{document}${\rm A}^2 \Pi$\end{document} and \begin{document}${\rm C}^2 \Pi$\end{document}, \begin{document}${\rm B}^2 \Sigma^+$\end{document} and \begin{document}$3^2 \Sigma^+$\end{document} respectively. The spectrum and molecular constants are in good agreement with the recently obtained theoretical calculations and experimental values except the adiabatic excitation energy. It may be due to the fact that the effect of the interaction of electronic states is taken into account. The transition properties such as Frank-Condon factor and radiation lifetime are also given. It can be seen that the 0-0 band of \begin{document}${\rm B}^2 \Sigma^+$\end{document}−\begin{document}${\rm X}^2 \Sigma^+$\end{document} transition has the largest Franck-Condon factor of 0.861288, and the diagonalization is obvious, which is the condition for laser cooling. The lifetime of \begin{document}${\rm B}^2 \Sigma^+$\end{document}−\begin{document}${\rm X}^2 \Sigma^+$\end{document} transition is 38.89 ns, which is in accordance with the experimental value 39.6 ns ± l.6 ns. These precise spectral transition characteristics may provide theoretical support for further constructing the laser cooling scheme of Sr35Cl molecule.