LAUSR

Density‐functional theory based, first‐principles spin‐polarized calculations of the structural, electronic, magnetic, optical, and thermoelectric characteristics of K2OsX6 (X = Cl, Br) are presented. Structural optimization confirms the stability of these compounds in ferromagnetic phase with curie temperatures of 726 K (K2OsCl6) and 557 K (K2OsBr6). The calculated formation and cohesive energies present K2OsX6 compounds as thermodynamically stable and strongly bonded. Computed electronic properties explore both the compounds as half‐metallic. In the spin‐up channel, they exhibit semiconducting nature, having direct band gap values of 2.69 eV (K2OsCl6) and 2.1 eV (K2OsBr6), while in spin‐down configuration, they turn into metals. The calculated ferromagnetic total spins magnetic moment per formula unit is 2.00 μB for both the compounds with major contributions from Os‐t2g states. The reasonable values of optical parameters like optical conductance, absorption factor, refractive index, and reflectivity potentially dedicate these compounds for optoelectronic applications. The calculated positive Seebeck coefficient with maximum values of 76.4 μV/K, for K2OsCl6, and 99.9 μV/K, for K2OsBr6, represent these compounds as p‐type materials. The proposed compounds may achieve consideration in spintronic, thermoelectric, and optoelectronic devices.