高压下CaF_2结构相变和光学性质的第一性原理计算  

First-Principles Study of Structural Stabilities,Electronic and Optical Properties of CaF_2 under High Pressure

作　　者：杨晓翠[1] 赵玉伟[2] 高忠明[2] 刘鑫[2] 张立新[2] 王晓明[2] 郝爱民[2,3] 

机构地区：[1]白城师范学院物理系,吉林白城137000 [2]河北科技师范学院理化学院,河北秦皇岛066004 [3]燕山大学亚稳材料制备技术与科学国家重点实验室,河北秦皇岛066004

出　　处：《高压物理学报》2010年第3期225-230,共6页Chinese Journal of High Pressure Physics

基　　金：白城师范学院重点科研项目(200803);河北科技师范学院博士基金(2008YB001);中国博士后科学基金(20090450924)

摘　　要：利用基于密度泛函理论的第一性原理方法,计算了在压力作用下CaF2的结构相变和光学性质。结果证实了CaF2的压致结构转变的顺序是从氟石结构(空间群Fm3m)转变到PbCl2型结构(空间群Pnma),然后继续转变为Ni2In型结构(空间群P63/mmc)。在Fm3m和Pnma两种结构中,电子带隙随着压力的增加而增加,而在P63/mmc结构中,带隙随着压力的增加开始下降。实验结果显示,直到210 GPa,CaF2没有发生由绝缘体到金属的转变。据此推测,CaF2的金属化压力高于300 GPa。还讨论了压力对CaF2光学性质的影响。An investigation on the structural stabilities and electronic properties of CaF2 under high pressure was conducted using first-principle calculation based on density functional theory（DFT） with the plane wave basis set as implemented in the CASTEP code.Our results demonstrate that the sequence of the pressure-induced phase transition of CaF2 is the fluorite structure（Fm3m） to the PbCl2-type structure（Pnma）,and to the Ni2In-type phase（P63/mmc）.The energy gap increases with pressure in the Fm3m and Pnma phases,then begins to decrease in the P63/mmc phase.The band gap overlap metallization does not occur up to 210 GPa.It is predicted that the metallization pressure of CaF2 should be over 300 GPa.The pressure effect on the optical properties is discussed.

关 键 词：第一性原理计算 相变 高压 光学性质 

分 类 号：O521.2[理学—高压高温物理]