中文摘要：

采用基于赝势平面波基组的密度泛函理论方法,对非心结构β-LiAsSe2晶体的电子结构进行研究,并预测其光学性质.计算结果表明,在线性光学性质方面,LiAsSe2在红外区域具有很高的双折射率（大于0.5）,它对长波长太阳光的吸收能力和光电转化效率要优于铜铟硒基半导体材料.对于非线性光学（NLO）性质,与AgGaSe2相比,LiAsSe2在红外区具有很强的倍频（SHG）效应,静态倍频系数d33约为836.5pm·V-1,但它在红外区的透光性不如AgGaSe2.通过能带结构分析可知,体系的倍频效应主要来源于含有Li成分的部分价带与靠近导带底空带之间的跃迁.

英文摘要：

We used density functional theory based on the pseudo-potential plane wave basis set to investigate the electronic structure of the β-LiAsSe2 crystal with a non-centrosymmetric structure and the optical properties. Our results indicate that for the linear optical properties the birefringence of LiAsSe2 is very large （0.5） in the infrared region. The adsorption ability and photoelectric conversion efficiency of long wavelength sunlight for LiAsSe2 were found to be superior to those of CuInSe2. Regarding the nonlinear optical （NLO） characteristics, LiAsSe2 showed a very large NLO second harmonic generation （SHG） response in the infrared region and the SHG coefficient （d33） of LiAsSe2 is about 836.5 pm·V -1. However, poor transmission of light in the infrared region is predicted for LiAsSe2 compared to AgGaSe2. By an analysis of the band structure, the SHG response of the system could be attributed to transitions from valence bands that were mixed with contributions from Li to the unoccupied bands near the bottom of the conduction bands.