关键词: 
密度泛函理论 /
高压 /
剪切弹性系数 /
结构相变

摘要: 运用密度泛函理论研究了钒(Vanadium)在高压下的结构相变。 通过对体心立方(bcc)结构的钒在不同压强下剪切弹性系数C44的计算， 发现当压强约95 GPa时 C44＜0， 说明体心立方结构的钒在此条件下是不稳定的。 进一步计算分析得到钒在高压下发生了从体心立方到菱面体 (Rhombohedral)的结构相变， 相变压强约70 GPa， 这一结果与最近的实验结果符合。 还首次发现当压强约380 GPa时， 将会发生菱面体到体心立方的结构相变， 这有待实验的验证。
We have studied the structure phase transition of Vanadium under high pressures by density function theory. A mechanical instability in the shear elastic constant (C44) has been found for bodycentred cubic(bcc) Vanadium at about 95 GPa, which indicates the existence of the structural transition. By calculation and analysis, we found that there was a bccrhombohedral structure transition at the 70 GPa, which is consistent with the experiment data. Our calculations also firstly gave that there was a rhombohedralbcc structure transition at about 380 GPa, which needs to be verified by the experiment.