Mg_2Si单轴应变的结构和电子性能

Structural and Electronic Properties of Mg_2Si Under Uniaxial Strains

基于密度泛函理论的第一性原理计算方法研究了Mg2Si半导体沿[001]方向单轴应变下的结构、力学性质以及电子性质。计算结果表明:无应变时晶格参数和弹性常数与其他理论及实验值吻合的很好。施加应变后,其与应变方向垂直的晶格常数随应变值呈近似线性变化。通过应力-应变曲线和Born力学稳定性判据,确定了Mg2Si化合物在拉伸、压缩过程中的稳定范围和理想强度。Mg2Si的电子布居和电子态密度分析,表明Si-Mg之间的显示离子键特性,并给出了在拉伸压缩过程中Mg和Si原子轨道电子对总的态密度影响。

The structural, elastic and electronic properties of Mg2Si under uniaxial strain along [ 001 ] are successfully obtained using the first-principle plane-wave pseudopotential method. The results show that the lattice parameters and elastic parameters are in better agreement with other＇ s theoretical and experimental data of unstrained structure. For the strained structures, the stable structures and idea strength of Mg2Si are ensured through using strain-stress curve and Born mechanical stability conditions. Calculations of electron population and density of states are also performed to describe the orbital mixing and the nature of chemical bonding. The total, s-partial and d-partial DOS of Mg and Si atoms are given respectively. The results indicate that the bonding interactions （Si-Mg） in the Mg2Si crystal are ionic.