In this work, detailed DFT calculations of the structural, mechanical and electronic properties of crystalline CaSi₂ with four different structures in the pressure range of 0–50 GPa are performed by GGA-PBE. It is found that the Enthalpy differences imply that the R3̄m phase → I4₁/amd phase → P6/mmm phase transition in CaSi₂ occur at P1=2.5GPa, P2=33.5GPa by using the XC of GGA, which is consistent with previous experiments and theoretical conclusions. Besides, the elastic stability criterion is used to study the change of the elastic constant of CaSi₂ under pressures. In particular, the bulk modulus B, shear modulus G, Young’s modulus E, sound velocity v and brittleness and toughness properties of CaSi₂ under pressures are comprehensively studied for the first time. Finally, the changes of the anisotropy factor of CaSi₂ are studied under different pressures, and the electronic structure is studied in detail.

中文翻译：

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高压下CaSi2的四种结构的结构、力学和电子结构的理论研究

在这项工作中，通过 GGA-PBE 对在 0-50 GPa 压力范围内具有四种不同结构的晶体 CaSi ₂的结构、机械和电子特性进行了详细的 DFT 计算。发现焓差意味着 R3̄m相→I4 ₁ /amd 阶段→_{CaSi 2}中的P6/mmm 相变发生在磷1=2.5帕,磷2=33.5GPA 采用 GGA 的 XC，这与之前的实验和理论结论是一致的。此外，弹性稳定性准则用于研究CaSi ₂在压力下弹性常数的变化。特别是体积模量乙, 剪切模量G, 杨氏模量乙, 声速v首次全面研究了CaSi ₂的压力脆性和韧性性能。最后研究了不同压力下CaSi ₂各向异性因子的变化，详细研究了电子结构。