Revealing the Electronic, Optical, and Thermoelectrical Properties of MgAu<sub>2</sub>F<sub>8</sub> through DFT Calculations

Fluoride materials are renowned for their exceptional optical transparency, ionic conductivity, and chemical stability, making them indispensable in a wide range of technological applications. Despite the previous extensive research on simple metal fluorides, the complex metal fluoride family—particularly compounds with AB2F8 stoichiometry—remains largely unexplored. In this work, we present the first comprehensive density functional theory (DFT) investigation of the rare and formerly unreported MgAu2F8 complex metal fluoride, systematically revealing its electronic, optical, and thermoelectric properties under varying hydrostatic pressures. Our results reveal that MgAu2F8 undergoes a remarkable transformation from a wide-bandgap semiconductor at ambient conditions to a highly reflective, optically anisotropic, and metallic state under extreme compression. Pressure-induced band gap narrowing, enhanced optical absorption, and dramatic increases in electrical and thermal conductivities are observed, highlighting the material’s extraordinary sensitivity to external stimuli. The ability to finely tune these properties through pressure engineering positions MgAu2F8 as a promising candidate for advanced optoelectronic, thermoelectric, and pressure-sensing applications. This work not only expands the frontier of complex fluoride research but also underscores the power of DFT-based computational approaches in accelerating the discovery and design of next-generation functional materials.