High-throughput computational materials screening of transition metal peroxides

Semiconductor materials of abnormal stoichiometric ratio often exhibit unique properties, yet it is still a challenge to determine the structures of such materials in an efficient way. Herein, we propose a method for structurally biased screening according to the coordination numbers and the numbers of Wyckoff positions, balancing the atom local environment and the global symmetry of structures. Based on first-principles calculations, we have predicted two metastable peroxides P2₁/c-ScO₂ and Pmmn-TiO₃ with more than six coordination points. For these two structures, the most stable intrinsic defect is the oxygen vacancy (V_O) at the peroxide anion (O2-2), which induces the absence of antibonding orbital formed by O2-2 near the valence band maximum. With the introduction of V_O, the decrease of coordination numbers leads to charge recombination, and results in the appearance of an ordered phase TiO_2.5 with stronger Ti-O orbital hybridization. The proposed method presents a promising and feasible approach for the screening of novel compounds.