中文摘要：

压电的性质[0001 ] 面向的 ZnO nanowires 经由密度被调查功能的理论(DFT ) 。ZnO nanowires 的轴的有效压电的系数比体积价值显著地大，并且当 nanowire 尺寸减少，系数增加。改进每 Zn-O 对和泊松比率的改进来自体积的减小，这被证明。进一步的学习证明 ZnO nanowires 的宏观的极化行为被水晶结构参数和表面原子的比率决定，并且分析表情被获得。这个工作提供 ZnO nanowires 的压电的尺寸效果的更深的理解并且阐明在这个题目上报导的混乱。

英文摘要：

The piezoelectric properties of [0001]-oriented ZnO nanowires are investigated via density functional theory （DFT）. The axial effective piezoelectric coefficient of ZnO nanowires is significantly greater than the bulk value, and the coefficient increases as the nanowire size decreases. It is proved that the enhancement comes from both the reduction of volume per Zn-O pair and the enhancement of the Poisson＇s ratio. Further study shows that the macroscopic polarization behavior of ZnO nanowires is determined by the crystal structure parameters and the ratio of surface atoms, and an analytic expression is obtained. This work provides a deeper understanding of the size effects of the piezoelectricity of ZnO nanowires and sheds some light on the confusion reported on this subject.