First principles study on the electronic, elastic and vibrational properties of marcasite-type OsP2

Penta-OsP2 and penta-Rhs2 sheets derived from marcasite and pyrite with low lattice thermal conductivity

“…It is also worth mentioning that the band gap of penta-OsP 2 at the PBE level (0.44 eV) is lower than that (0.92 eV) of marcasite-phase OsP 2 . 58 This is because the energy level broadening that usually happens during the increase in dimensionality is overwhelmed by the changes in electronic states due to the changes in the geometry of OsP 2 . While penta-RhS 2 has a direct band gap of 0.93 eV at the high-symmetry point Γ , the band gaps of both the two pentagonal sheets are smaller than that of the synthesized penta-PdSe 2 (∼1.3 eV) 22 and penta-NiN 2 (∼1.1 eV), 26 which have been found to be desirable for thermoelectric applications.…”

“…58 It is also worth noting that penta-OsP 2 possesses a signicant negative Poisson's ratio of À0.24 along the diagonal direction, which is not found in marcasite-phase OsP 2 . 58 It is worth noting that the electronic properties of a system with a NPR would change signicantly under external stress due to the variation of the orbital interactions of atoms induced by the changes in the bond lengths and bond angles, as demonstrated in multilayer graphene. 59 More discussions on the mechanical properties of the two structures are presented in Text S2 and Fig.…”