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本文利用多体格林函数理论,计算了石墨相g-CN的准粒子能带结构和光吸收谱.准粒子能带结构通过GW方法进行计算.考虑电子-空穴相互作用,通过求解Bethe-Salpeter方程获得了激发能和光吸收谱.计算的准粒子带隙为4.88 e V,极大地修正了密度泛函理论的结果.光吸收谱在4.85 e V处有一个强烈的吸收峰,这与实验结果一致.该吸收峰对应的激子空间分布局域,激子束缚能达到2.32 e V.在低能量处有一些来源于?轨道的暗激子态,对光化学过程产生一定的影响.
In this paper, the quasi-particle energy band structure and optical absorption spectra of graphite phase g-CN were calculated by the multi-body Green’s function theory.The quasi-particle energy band structure was calculated by the GW method.According to the electron-hole interaction, by solving the Bethe-Salpeter equation The excitation energy and optical absorption spectra were obtained.The calculated quasi-particle band gap was 4.88 eV, which greatly corrected the results of density functional theory.The optical absorption spectrum had a strong absorption peak at 4.85 eV, which was consistent with the experimental results The absorption peak corresponds to the spatial distribution of excitons, and the exciton binding energy reaches 2.32 e V. There are some excitonic states derived from the orbital at low energies, which have an impact on the photochemical process.