CAS Key Laboratory of Functional Materials and Devices for Special Environments, Xinjiang Technical Institute of Physics & Chemistry, CAS, Xinjiang Key Laboratory of Electronic Information Materials and Devices, 40-1 South Beijing Road, Urumqi 830011, China.
Phys Chem Chem Phys. 2019 Feb 27;21(9):5142-5147. doi: 10.1039/c8cp07894g.
First-principles studies of the crystal structures, electronic structures and optical properties of noncentrosymmetrical (NCS) K3AsS4, Li3AsS3, Pb9As4S15 and Ag3AsS3 have been performed by means of density functional theory. Via a theoretical method to compute the intensity of the lone pair stereochemical activity of an As-S group, the correlated mechanism among the crystal structures, the stereo-chemical activity of lone pairs on As and the second harmonic generation (SHG) response has been clarified. The results prove that the SHG response is not only attributed to the lone pair stereochemical activity of the As-S group but also related to the direction of the forming layers in the crystal structure arrangement. Besides, the quantitative method for the stereo-chemical activity of lone pairs is universal, which is valid for other lone pair systems like those containing Pb2+, Bi3+, Sn2+, etc. The findings facilitate the exploration of materials that may exhibit a relatively large second order NLO reaction and can be used in infrared applications.
采用密度泛函理论，对非中心对称（NCS）的 K3AsS4、Li3AsS3、Pb9As4S15 和 Ag3AsS3 的晶体结构、电子结构和光学性质进行了第一性原理研究。通过一种计算 As-S 基团孤对立体化学活性强度的理论方法，阐明了晶体结构、孤对立体化学活性与二次谐波产生（SHG）响应之间的相关机制。结果表明，SHG 响应不仅归因于 As-S 基团的孤对立体化学活性，还与晶体结构排列中形成层的方向有关。此外，孤对立体化学活性的定量方法是通用的，适用于其他含有 Pb2+、Bi3+、Sn2+ 等孤对体系的物质。这些发现有助于探索可能表现出较大二阶 NLO 反应并可用于红外应用的材料。
