First-principles study of structural, elastic, and optoelectronic properties of alkali metal tetrafluoroaurate materials MAuF₄ (M = Na, K, and Rb)

This research focuses on the theoretical investigation of the structural, elastic, electronic, and optical properties of alkali metal tetrafluoroaurate NaAuF₄, KAuF₄, and RbAuF₄ ternary compounds through ab-initio calculations within the framework of density functional theory using the pseudopotential plane wave method. The structural parameters are consistent with the experimental values reported in the literature. Since these compounds are ductile by nature, the elastic constants support this claim. Numerous anisotropy indexes are examined in order to validate the elastic anisotropic nature of these materials. Furthermore, employing 3D shapes has allowed for the implementation of additional innovative approaches. These materials can be classified as semiconductors based on their computed electronic structure. In contrast to KAuF₄ and RbAuF₄, which are semiconductor materials with an indirect band gap, NaAuF₄ is a semiconductor with a direct band gap. Finally, in-depth research has been done on optical properties, including the real and imaginary components of the dielectric function, the refractive index, and the absorption coefficient. Due to their broad optical absorption in the UV range, these materials may be useful for the manufacture of UV photodetectors. Unfortunately, there is no comparable earlier study available. Hence, upcoming experimental investigations are anticipated to be inspired by this theoretical research.