Structure and Function of Heteroanionic Materials

The goals of the project are to (1) implement and extend a heteroanionic materials design scheme for understanding the complex interplay among local and extended crystal structure, anion order, and electronic and optical responses in new regimes; and (2) To advance new heteroanionic materials and structures exhibiting superior functionalities and/or responses not currently available in homoanionic materials. The project utilizes a computational strategy, which integrates group theoretical techniques, derivative-structure generation tools, and density functional theory (DFT), to understand the electronic and optical properties of oxynitrides, oxysulfides, and oxyfluoride within three domains: (A) Geometric and Chemical Control of Noncentrosymmetry for Acentric Function; (B) Probing MIT Mechanisms and Materials Discovery with Multiple Anions; and (C) Novel Routes to Anion-Ordered Topological Semimetals. The intellectual merit of the research is in elucidating the fundamental role of symmetry, electronic structure, topology, and spin-orbit coupling in theories of novel electronic and quantum states to embody them by design in real heteroanionic materials. Success in the project will lead to model frameworks that are both descriptive and predictive, and may be expanded to other materials. Knowledge created here will advance the repertoire of structure-based design strategies. A deep theoretical understanding of novel heteroanionic materials, which by definition are poorly understood, can be viewed as transformative in accelerating materials discovery, which is an important national priority.