摘要:
运用第一性原理平面波赝势和广义梯度近似方法,对闪锌矿结构(ZB)和氯化钠结构(RS) ZnS的状态方程及其在高压下的相变进行计算研究,分析相变点附近的电子态密度、能带结构和光学性质的变化机理.结果表明:通过状态方程得到ZB相到RS相的相变压强值为18.1 GPa,而利用焓相等原理得到的相变压强值为18.0 GPa;在结构相变过程中, sp3轨道杂化现象并未消失, RS相ZnS的金属性明显增强;与ZB相ZnS相比, RS相ZnS的介电常数主峰明显增强,并向低能方向出现了明显偏移,使得介电峰向低能方向拓展,在低能区电子跃迁大大增强.
关键词:
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硫化锌
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相变
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电子结构
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光学性质
Abstract:
Equation of state and phase transformation under high pressure of ZnS in zinc blende (ZB) and rock salt (RS) structures have been calculated by means of plane wave pseudo-potential method (PWP) with generalized gradient approximation (GGA). The electronic density of states, band structure and optical properties of change mechanism have been discussed near the point of phase transformation. The results reveal that the transition pressure of ZnS from ZB to RS phase is 18.1 GPa by the equation of state, but it is 18.0 GPa obtained with the enthalpy equal principle. The sp3 hybrid orbital has not been eliminated and the metalic behavior of RS ZnS is enhanced significantly in the structural phase transition process. By comparing RS phase with ZB one, the main peak of the dielectric constant in RS ZnS becomes higher and shifts to the lower energy direction apparently, and other dielectric peaks are also extended to lower energy direction, at the same time the electronic transitions are enhanced in the low energy region.
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