六方Al_(4)SiC_(4)弹性性质、电子结构和光学性质的第一性原理计算

First-principles calculations of the elastic properties,electronic structure and optical properties of hexagonal Al_(4)SiC_(4)

采用基于密度泛函理论(DFT)的第一性原理计算方法系统地研究了Al_(4)SiC_(4)的晶体结构、弹性常数、电子结构和光学性质,并对结果进行了理论分析.计算得到的晶格常数和弹性常数均与实验值及其它计算值相符,并说明了六方Al_(4)SiC_(4)的晶体结构是稳定的;计算得到了六方Al_(4)SiC_(4)的体积、剪切、杨氏模量及泊松比与文献值一致,Al_(4)SiC_(4)的禁带宽度为1.076 eV.计算得到了六方Al_(4)SiC_(4)在(100)和(001)方向上的光学响应函数随光子能量的变化关系,包括复介电函数、复折射率、吸收光谱及反射光谱.在(100)和(001)方向上,计算得到其静态介电常数分别为7.74和8.96,折射率分别为2.78和2.99.计算结果可以为相关应用提供理论依据.

The crystal structure,elastic constants,electronic structure and optical properties of Al_(4)SiC_(4) have been systematically investigated using the first principles calculation method based on density functional theory.The calculated lattice constants and elastic constants are consistent with the experimental and calculated values,and it shows that the hexagonal Al_(4)SiC_(4) crystal structure is stable.The calculated bulk,shear,Young’s modulus and Poisson’s ratio of hexagonal Al_(4)SiC_(4) are in accordance with the values in the literature.The calculated band gap of the Al_(4)SiC_(4) is 1.076 eV.The changes of optical response functions of hexagonal Al_(4)SiC_(4) in the(100)and(001)directions with photon energy are calculated,including complex dielectric function,complex refractive index,absorption spectrum and reflection spectrum.In the(100)and(001)directions,the static dielectric constants are 7.74 and 8.96,respectively,and the refractive indexes are 2.78 and 2.99,respectively.The calculated results can provide theoretical basis for related applications.