The impact of anionic group arrangement on the optical properties of the arsenate series
Abstract
This study employs first-principles calculation methods to systematically investigate the relationship between the electronic structure and optical properties of arsenate crystals containing alkali metals, alkaline earth metals, and transition metals, with a particular focus on the impact of structural-inducing anisotropy disparity on their optical properties. Through Response Electron Distribution Anisotropy (REDA) methods and polyhedral distortion index D assessments, it is confirmed that the [AsO4] group is the main contributor to optical anisotropy. Also, the results indicate that the density and arrangements of the [AsO4] group significantly affect optical anisotropy, with the high density and the 'Neat Arrangement' (NA) serving as the optimum. For non-centrosymmetric structures with second-harmonic generation (SHG) effects, such as A3AsO4 (A=Li, Na) and B3(AsO4)2 (B=Mg, Ca), the analysis indicates that the [AsO4] group is the source of SHG, suggesting its potential as a nonlinear optical functional group. However, the SHG coefficients are influenced by the arrangement of anionic groups; a symmetrical arrangement leads to a larger SHG effect.