摘要:
采用密度泛函理论的定域密度和一般梯度近似,研究了Si3P4 5个相的结构、电子和弹性性质.考虑的Si3P4结构包括分别具有空间群P63/m,Fd-3m,P-42m,IM-3M,P-43m的β,γ,膺立方、立方和缺损立方相.总的能量计算表明,具有缺损闪锌矿结构的膺立方和缺损立方相相对于其它相能量最低,因而是最稳定的2个相.弹性常数计算表明,两个相对稳定的相有大的应变模量,因而结构上较硬.能带结构和分波态密度计算表明,在两种近似下,膺立方和缺损立方是半导体,而β,γ和立方相是金属.
Abstract:
Using local-density approximation (LDA) and generalized-gradient approximation (GGA) based on density-functional theory (DFT), we investigated the structural, electronic and elastic properties of the five crystal phases of Si3 P4, i.e. β-,γ-, pseudocubic-, cubic-, and cubic-defect-Si3P4 phases, with their space groups P63/m, Fd3m, P-42m, IM-3M, and P-43m, respectively. Total-energy calculations indicated that the pseudocubic and the defect cubic phases with their defect zinc-blende structures are energetically favorable relative to other Si3P4 phases.The calculation of elastic constants showed that the two energetically favored phases have large shear moduli as compared to those obtained in the other phases. The band-structure and partial density-of-states reveal that pseudocubic and defect cubic phases are semi-conducting, while β,γ and cubic phases are metallic.
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