0～15 GPa外压下ZnO结构相变的第一性原理研究

利用第一性原理的计算方法,结合热力学和弹性力学的计算详细分析0～15 GPa外压下ZnO的结构、弹性模量和电子结构.结果表明:在研究压强范围内,B4结构的ZnO能量始终比B3结构的低,但随着外压的增加,无论是B4结构还是B3结构,都会在一定压强下转变成B1结构.B4至B1的压强转变点为12.4 GPa,B3至B1的压强转变点是11.8 GPa.B4结构转变成B1结构的瞬间,体系体积缩小约17%.结果与已有的实验与理论结果相符.B4结构的ZnO剪切模量在6～8 GPa时急剧下降,与已有的实验和理论计算结果相符.电子结构特征表明,随着外压的增强,体系中Zn 3d电子与O 2p电子相互作用减弱.

First-principles Study of Structural Transformation of ZnO Under Low Pressures

Structural,elastic,and electronic properties of B4,B3,and B1 ZnO under 0～15 GPa are studied with first-principles method combined with energe-of-state and elastic calculations.It shows that under 0～15 GPa,the energy of B4 ZnO is always lower than that of B3 ZnO.Either B4 or B3 transforms to B1 at a critical pressure,i.e.,11.8 GPa for B4 and 12.4 GPa for B3.As B4 transforms to B1,volume of the system reduces to about 88.3% of the initial value.The results agree with available experimental and theoretical data.The shear modulii reduce rapidly as the pressure is larger than 6 GPa,which means that some structural change may happen.It agrees with recent experimental results.Electronic properties show that the interaction between Zn 3d and O 2p reduces as the pressure increases.