中文摘要：

利用基于密度泛函的第一性原理,计算了在压力作用下Si的结构相变和弹性性质。晶胞总能的计算结果表明,Si在11.7 GPa压力下发生了从立方金刚石结构（Si-Ⅰ）到四方结构（Si-Ⅱ）的转变。能带结构和态密度的计算结果显示,Si-Ⅰ是具有间接带隙的半导体,带隙为0.71 eV,Si-Ⅱ呈现金属的能带结构特性;Si-Ⅰ和Si-Ⅱ费米面附近的能带结构主要来自于2p电子的贡献。高压下Si-Ⅰ的弹性系数计算结果表明,弹性系数C11,C12和C44均随压力的增加呈现线性增大的规律。

英文摘要：

An investigation on structural stability and elastic properties of Si under high pressure is conducted using first-principles calculations based on density functional theory （DFT）. Our results show that a structural transformation from Si- I to Si- II occurs at 11.7 GPa and that Si- I has indirect band structures with band gap of 0. 71 eV; and Si- II is metallic with several overlaps between conduction bands and valence bands. In addition, the results indicate that the elastic constants C11, C12 and C44 of Si-I increase linearly with pressure.