Structural and Electronic Properties of the Predicted Two-dimensional AsP2X6 (X=S,Se): First-principles Calculations
摘要
The structural, relative stability, and electronic properties of two-dimensional AsP2X6 (X=S, Se) were predicted and studied using the particle-swarm optimization method and first principles calculations. We proposed two low energy structures with P312 and P-31m phases, both of which the structures are hexagonal in shape and show non-centrosymmetry for the P312 phase and centrosymmetry for the P-31m phase. According to our results, two structural phases are found to be stable thermally and dynamically. The P312 phase of AsP2X6 (X=S, Se) are indirect semiconductors with band gaps of 2.44 eV(AsP2S6) and 2.18 eV(AsP2Se6) at the HSE06 level, and their absorption coefficients are predicted to reach the order of 105 cm−1 from visible light to ultraviolet region, but the main absorption is manly in the ultraviolet region. The P-31m phase of AsP2X6 (X=S, Se) exhibits metal character with the Fermi surface mainly occupied by the p orbital of S/Se. Remarkably, estimated by first principles calculations, the P-31m AsP2S6 is found to be an intrinsic phonon-mediated superconductor with a relatively high critical superconducting temperature of about 13.4 K, and the P-31m AsP2Se6 only has a superconducting temperature of 1.4 K, which suggest that the P-31m AsP2S6 may be a good candidate for a nanoscale superconductor.