Mg_2C高压性质的从头计算法研究  

The phase transitions,electronic structures and optical properties of Mg_2C under pressure:ab initio calculations

作　　者：余飞[1,2] 周永宏[1] 孙久勋[2,3] 

机构地区：[1]西华师范大学物理与电子信息学院,南充637002 [2]电子科技大学应用物理系,成都610054 [3]中国工程物理研究院流体物理研究所冲击波物理与爆轰物理实验室,绵阳621900

出　　处：《原子与分子物理学报》2011年第1期145-150,共6页Journal of Atomic and Molecular Physics

基　　金：西华师范大学科研启动基金(05B14)

摘　　要：运用基于密度泛函理论的平面波赝势方法,结合广义梯度近似,系统地研究了Mg_2C在高压下的结构相变、电子结构和光学性质.计算结果表明Mg_2C在高压下将发生两次相变,一次是从反萤石到反氯化铅结构的一阶相变在30.09 GPa,另一次是从反氯化铅结构到Ni_2In型结构的二阶相变在260 GPa.此外,对压力下电子结构和光学性质的分析表明,Mg2C的带隙宽度随着压力增加而增加,与Mg2Si在压力下表现出金属性有很大不同.The phase transitions, electronic structures and optical properties of Mg2C were investigated using the first-principles plane-wave method within the pseudopotential and generalized gradient approximations. The calculated results demonstrate that Mg2C undergoes two pressure-induced phase transitions： one is a first-order phase transition from the anti-fluorite structure to the anti-cotunnite structure at 20.09 GPa, and the other is a second-order phase transition from the anti-cotunnite structure to the Ni2In-type structure at 260 GPa. Moreover, the electronic and optical properties of Mg2C under pressure were discussed; they show that the band gaps become broader with the increase of the pressure. This is different from Mg2Si, which has become metallic at high pressure.

关 键 词：密度泛函理论 高压相变 电子结构 光学性质 

分 类 号：O414.13[理学—理论物理] O521[理学—物理]