Type-1 Pentagonal Tiling Realized in 2D Penta-SrP2 Sheet

According to the systematic classification of pentagon-based two-dimensional (2D) materials [ Phys. Rep. 2022, 964, 1], only type-2 and type-4 out of the 15 pentagonal tiling patterns have been realized in 2D materials so far. Here, we propose the first stable pentagon-based 2D material characterized by the type-1 pentagonal tiling pattern named penta-SrP2. We find that penta-SrP2 is not only thermally and mechanically stable but also dynamically stable when the temperature is above 200 K derived from the calculations by taking both phonon renormalization and thermal expansion into consideration. Moreover, the penta-SrP2 sheet is semiconducting with an indirect band gap of 0.96 eV. These findings expand the family of pentagon-based 2D materials in morphology and provide a new perspective to explore the dynamical stability of high-temperature phases.