Challenges and Advances in Elucidating the Electronic Circular Dichroism of Crystalline Materials through
Wenkai Zhao1, Xinyu Sun2, Sehrish Gull1
1Frontiers Science Center for New Organic Matter, Tianjin Key Lab for Rare Earth Materials and Applications, National Key Laboratory of Semiconductor Laser, Academy for Advanced Interdisciplinary Studies, Renewable Energy Conversion and Storage Center (RECAST), School of Materials Science and Engineering, Nankai University, Tianjin 300350, China.
Abstract:
The electronic circular dichroism (ECD) of crystalline materials is governed by physical effects that are absent in isolated-molecule theory. Bloch-state delocalization makes position-operator matrix elements ill-defined and requires Berry-connection formulations of the periodic optical-activity response, while excitonic effects redistribute oscillator strength across the band gap. This Perspective critically surveys the hierarchy of first-principles methods that have been established to address these challenges. Molecular-cluster time-dependent density functional theory (TDDFT) provides chemical intuition and mechanistic insight but cannot represent the complete periodic response and can underestimate long-range crystal field effects. Periodic independent-particle calculations incorporate the crystalline environment and band-geometric response, whereas self-consistent coupled-perturbed approaches additionally include crystal-orbital relaxation. Adaptive Brillouin-zone sampling can accelerate convergence for localized one-particle contributions, although nonuniform meshes complicate momentum conservation in the correlated treatments. GW-BSE provides a rigorous framework for excitonic optical activity, whereas maximally localized Wannier function interpolation efficiently converges the DFT-level periodic quantities used to analyze the band-geometric response. A generally validated workflow that combines the BSE-level excitonic response with all geometric and interpolation ingredients has not yet been established. Finally, we discuss open challenges including fully relativistic treatments of chiral rare-earth halide perovskites and single-crystal anisotropy measurements.
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