高压下BaF_2相变及光学性质的第一性原理研究(英文)

Phase Transition and Optical Properties of BaF_2 under High Pressure:A Density Functional Theory Study

基于第一性原理赝势方法研究了高压下BaF2的晶体结构,结果表明在高压下BaF2将发生相变,依次为常压立方相、正交相、六角相.电子结构的研究表明,对于立方相和正交相,带隙随着压强的增加而增加,高压六角相带隙随压强增加而减小,但3个高压相均呈现出非金属性.最后,讨论了高压下BaF2的光学性质.

First-principles calculations were performed on BaF2 using the generalized gradient approximation pseudopotential method.Our results demonstrate that the sequence of the pressure-induced phase transition of BaF2 is the cubic phase（Fm3m）,the orthorhombic phase（Pnma）,and the hexagonal structure（P63/mmc）.The energy band gap increases with pressure in the cubic and orthorhombic phases,but decreases in the hexagonal phase.We also discuss on the optical properties for the high pressure phases.