高压下ZnO的结构、弹性性质和吸收光谱的第一性原理研究

摘要

运用基于密度泛函理论(DFT)的平面波赝势方法(PWP),结合局域密度近似(LDA)以及广义梯度近似(GGA),系统地研究了ZnO的纤锌矿结构(B4结构),NaCl结构(B1结构)和CsCl结构(B2结构)在不同压强下的几何结构、弹性性质和吸收光谱.详细研究了ZnO发生的两次相变(B4→B1及B1→B2相变),得到了不同近似下的相变压强,以及两次相变过程中其弹性常数随压强的变化,并分析了这种变化与相变的关系.发现在高压作用下,ZnO的吸收光谱发生蓝移.通过计算结果和实验结果的比较可以看出,LDA近似下的计算结果更加符合实验结果.%The structural, elastic properties and absorption spectra of ZnO in wurtzite (B4), NaCl (B1) and CsCl(B2) structures are studied by plane wave pseudo-potential (PWP) method. The method is based on the density functional theory (DFT) within the local-density approximation (LDA) and generalized gradient approximation (GGA) approaches. The calculation gives out the respective structural phase transition pressures for two transitions (B4→B1, B1→B2). We investigate the behavior of the elastic constants C as function of pressure and show the relation between the behavior and the phase transition. The blue shifts of absorption spectrum of ZnO under high pressure are found. Comparing the results between experiment and computation,we can find that the calculation by LDA is in better agreement with the experiment.