Jia-Xiang Zhang, Alan Xu, Yang Chi, Xin-Tao Wu, Hua Lin, Qi‐Long Zhu
). Atomic space tessellating analysis reveals that ∼75% of the SHG contribution originates from S, particularly from localized S-3p nonbonding electrons-challenging conventional stereochemically active lone-pair (SCALP)-based contribution models that overlook the dominant role of S. Moreover, symmetry analysis identifies the polar screw axis as the favorable symmetry for high-SHG SCALP-based chalcogenides. This work transitions NLO material design from structural building-unit assembly to electronic-level engineering, opening new avenues for next-generation high-performance NLO materials.