Electronic structure and bonding in epitaxially stabilized cubic iron silicides.
Electronic structure and bonding in epitaxially stabilized cubic iron silicides.
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DOI：
10.1103/physrevb.48.4364
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发表时间：
1993-05
期刊：
影响因子：
--
通讯作者：
Maeder;von Känel H;Baldereschi
中科院分区：
文献类型：
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作者：
Maeder;von Känel H;Baldereschi
采用全势线性缀加平面波（FLAPW）方法对最近在Si（111）衬底上用分子束外延生长的两种体不稳定化合物FeSi（CsCl结构）和FeSi_2（CaF_2结构）的结构和电子性质进行了从头算研究.我们得到的平衡体晶格常数为2.72 u和5.32 u的FeSi和FeSi 2，分别。FeSi的态密度（DOS）与实验符合得很好，显示出金属性。与先前的计算结果一致，FeSi 2的DOS在费米能级处显示出大密度的d态，解释了体相的不稳定性。电子电荷分布揭示了一个小的电荷转移从Si到Fe原子球在这两种化合物。虽然在FeSi的Fe-Si键确实是部分离子，我们表明，在FeSi 2的电子分布对应于在Fe-Si键区域的共价电荷积累。相反的顺序在FeSi中的d-带相对于FeSi 2的理解在CsCl结构中的晶场分裂和Fe-Fe最近邻dd-相互作用，和一个强的Si p/Fe d键合的萤石结构，分别。
We present an ab initio full-potential linearized augmented plane-wave (FLAPW) study of the structural and electronic properties of the two bulk unstable compounds FeSi (CsCl structure) and FeSi2 (CaF2 structure) which have recently been grown by molecular beam epitaxy on Si(111). We obtain equilibrium bulk lattice constants of 2.72 u and 5.32 u for FeSi and FeSi2, respectively. The density of states (DOS) of FeSi agrees well with experiment, and shows metallic behavior. In agreement with a previous calculation the DOS of FeSi2 shows a large density of d-states at the Fermi level, explaining the instability of the bulk phase. The electron charge distributions reveal a small charge transfer from Si to Fe atomic spheres in both compounds. While in FeSi the Fe-Si bond is indeed partially ionic, we show that in FeSi2 the electron distribution corresponds to a covalent charge accumulation in the Fe-Si bond region. The reversed order of d-bands in FeSi with respect to FeSi2 is understood in terms of crystal field splitting and Fe-Fe nearest neighbor dd-interactions in the CsCl structure, and a strong Si p/Fe d bonding in the fluorite structure, respectively.