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利用基于密度泛函理论的第一性原理计算,本文研究了二十面体硼化砷(B12As2)在外部静水压强0～30GPa范围内的晶格结构变化。计算结果表明:二中心B-B键在高压下压缩率最大,硼二十面体基团相对比较稳定,外界压力对其影响较小。利用基于密度泛函微扰理论的计算,本文给出了在0～30GPa范围内B12As2晶体所有12个拉曼活性振动模的频率随外部静水压的变化,并给出了零压附近的压强系数和Grüneisen系数。计算结果表明,低频区有关As原子振动的模和频率为502.7cm-1的Eg模对于压力较为不敏感;高频区有关二中心B-B键振动的模对于压力最为敏感。
Based on the first principles calculations based on density functional theory, the lattice structure of icosahedral boride arsenic (B12As2) in the range of 0 ~ 30GPa of external hydrostatic pressure was studied. The results show that the compression rate of B-B bond in the center of the two centers is the highest under high pressure, and the B icosahedral groups are relatively stable and the external pressure has little effect on the B-B bond. Using the calculation based on the theory of density functional perturbation, this paper gives the change of the frequency of all 12 Raman modes of vibration of B12As2 crystal with the external hydrostatic pressure in the range of 0 ~ 30GPa, and gives the pressure near zero pressure Coefficient and Grüneisen coefficient. The results show that the mode of Eg vibration at low frequency region and the Eg mode at 502.7cm-1 frequency are relatively insensitive to pressure. The mode of high-frequency vibration of the B-B bond at the center is the most sensitive to the pressure.