碱土金属氧化物CaO的准粒子能带及光吸收谱

Quasiparticle Band Structure and Optical Absorption Spectrum of Alkaline-Earth Oxide CaO

本文使用多体摄动理论计算了碱土金属氧化物CaO的准粒子能带结构和光吸收谱。我们运用GW近似来改进密度泛函理论的局域密度近似对电子交换关联的处理,并计算了CaO准粒子能带。对于电子-空穴激发态,求解二粒子格林函数的Bethe-Salpeter方程可计算电子-空穴激发态和光吸收谱。计算得出CaO的能隙是7.3 eV,与实验结果7.1 eV符合较好。CaO光吸收谱的理论结果与实验数据也一致。特别是在计算CaO激发能最低的激子峰时,计算结果很好地再现了实验结果。

This paper reports the quasiparticle band structure and the optical absorption spectrum of alka-line-earth metal oxide CaO, using many-body perturbation theory. The quasiparticle band structure is calculated within the GW approximation. Taking the electron-hole interaction into consideration, electron-hole pair states and optical excitations are obtained by solving the Bethe-Salpeter equation for the electron-hole two-particle Green function. The calculated band gap for CaO is 7.3 eV, which is in good agreement with the experimental results of 7.1 eV. The theoretical result of optical absorption spectrum for CaO is also in agreement with the experimental data. In particular, the calculated excitation energy for the lowest exciton peak in the optical absorption spectrum of CaO reproduces the corresponding experimental result very well.