Structural, Electronic and Elastic Properties of Various Phases of Si_3P_4

摘要

Using the local-density approximation (LDA) and generalized-gradient approximation (GGA) based on density-functional theory (DFT), we investigate structural, electronic and elastic properties of the fivee phases of Si_3P_4, including β, γ, pseudocubic, cubic, and defect cubic phases with space groups P6_3/m, Fd-3m, P-42m, 1M-3M, P-43m, respectively. It is found that both pseudocubic and defect cubic phases with defect zinc-blende structures are energetically favored relative to other phases considered. The elastic constant calculations show that two energetically favored phases have large shear moduli relative to other phases. The band-structure and partial density-of-states calculations reveal that pseudocubic and defect cubic phases are semi-conducting, while β, γ, and cubic phases are metallic within both LDA and GGA.