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采用基于密度泛函理论的第一性原理方法研究BaC2高压相R■m的晶体结构、力学、热力学和电子结构等性质.计算结果表明:BaC2的I4mmm相较高压相R■m的离子性更强.在0K时,由BaC2的I4mmm相转变为R■m相的压强为3.6GPa,与实验结果相符.高压相R3m的弹性常数满足波恩-黄昆判据,因而其晶格力学性质稳定.布居数分析表明,在高压下,从Ba原子至C原子的电荷转移在I4mmm至R■m相变过程中所起的作用较大.
The first-principle method based on density functional theory (DFT) is used to study the crystal structure, mechanical, thermodynamic and electronic structure of BaC2 high voltage phase. The results show that the I4mmm of BaC2 is more ionic than R Strong at 0K, the transition from the I4mmm phase of BaC2 to R ■ the pressure of m phase is 3.6GPa, which agrees well with the experimental results.The elastic constants of the high-voltage phase R3m satisfy the Bonn-Huangkun criterion and the lattice mechanical properties are stable. The analysis of population numbers shows that the charge transfer from Ba atom to C atom plays a greater role during I4mmm to Rm phase transition under high pressure.