α-BeH_2电子结构与光学性质的第一性原理研究  

First principles study of electronic and optical properties of α-BeH_2

作　　者：彭敏[1] 韦建军[2] 张季[1] 刘丽[1,2] 

机构地区：[1]新疆工程学院基础部,乌鲁木齐830091 [2]四川大学原子与分子物理研究所,成都610065

出　　处：《原子与分子物理学报》2015年第4期653-659,共7页Journal of Atomic and Molecular Physics

摘　　要：基于密度泛函理论,采用赝势平面波方法研究了α-BeH2的结构、电子和光学性质.基态下,α-BeH2晶格常数a和体积弹性模量B0计算值与实验值及其它理论值一致.根据能带理论研究了α-BeH2基态下的能带结构、总态密度(DOS)和分波态密度(PDOS).经过分析发现α-BeH2为直接能隙半导体材料,能隙为5.44eV,与文献相比,本文计算的结果偏低,这主要是利用第一性原理中的局域密度近似(LAD)或广义梯度近似(GGA)交换关联能函数计算材料的带隙宽度或者磁耦合的理论结果均会偏低.通过对基态α-BeH2的Mulliken电荷分布和集居数的分析发现:α-BeH2属于离子键和共价键所形成的混合键化合物;α-BeH2的电荷总数分别来源于H1s轨道,Be2s和2p轨道.同时本文还分析研究了α-BeH2的光学介电函数、吸收系数、复折射率、反射系数和能量损失等光学性质.The structural, electronic and optical properties of α-BeH2 were investigated using the pseudo - potential plane wave method within the generalized gradient approximation in the frame of the density functional theory. The ground state properties, such as lattice constant a and bulk modulus B0, were calculated. These results are in good agreement with the experimental and other theoretical data. According to the band structural theory, we have studied the band structure, density of states （DOS） and partial density of states （PDOS） for α-BeH2 at the ground state. We found that α-BeH2 is a direct band gap semi -conductive material with the band gap 5.44 eV. The result is smaller than that in literature. This is because in response to the band gap or magnetic coupling theory, the calculated results using the local density approximation （LDA） or generalized gradient approximation （GGA） within the first principles are smaller than those using other method. We investigated the MuUiken charge and population of α-BeH2. It is indicated that α-BeH2 is a mix bond chemical compound consisting of ionic bond and covalent bond. The total charge of α-BeH2 derives from H ls, Be 2s and 2p orbits, respectively. At the same time, the dielectric function, adsorption coefficient, refractive index, reflection coefficient and loss function of α-BeH2 were calculated and investigated.

关 键 词：第一性原理 α-BeH2 光学性质 介电函数 

分 类 号：O443.5[理学—电磁学]