ABSTRACT

The structures, electronic and magnetic properties of the FeMg_n–1O_n and Fe₂Mg_n–2O_n (n = 1–8) clusters have been investigated by using first principles. For ground-state Fe₂Mg_n–2O_n clusters, they display a compromise that the Fe atoms prefer to exhibit the least coordination number and approach each other. Fe substitution can improve the structural stability of the Mg_nO_n clusters. The FeO, FeMg₄O₅, Fe₂Mg₂O₄, Fe₂Mg₅O₇ clusters show more chemical stability than the neighbors. The Fe–O bonds in the FeMg_n–1O_n and Fe₂Mg_n–2O_n clusters display covalent bond properties. For FeO, FeMgO₂, FeMg₂O₃, FeMg₄O₅, Fe₂O₂, Fe₂MgO₃ and Fe₂Mg₃O₅ clusters, the Fe atoms maintain higher spin densities while others are (almost) zero.

摘要

 已经使用第一性原理研究了 FeMg _{n –1} O _n和 Fe ₂ Mg _{n –2} O _n ( n = 1-8) 团簇的结构、电子和磁性能。对于基态 Fe ₂ Mg _{n –2} O _n团簇，它们表现出一种折衷，即 Fe 原子倾向于表现出最少的配位数并相互接近。Fe取代可以提高Mg _n O _n团簇的结构稳定性。FeO、FeMg ₄ O ₅、Fe ₂ Mg ₂ O_{如图 4 所示}，Fe ₂ Mg ₅ O ₇团簇比相邻的团簇具有更高的化学稳定性。FeMg _{n –1} O _n和 Fe ₂ Mg _{n –2} O _n簇中的 Fe-O 键显示出共价键性质。对于 FeO、FeMgO ₂、FeMg ₂ O ₃、FeMg ₄ O ₅、Fe ₂ O ₂、Fe ₂ MgO ₃和 Fe ₂ Mg ₃ O ₅ 簇中，Fe 原子保持较高的自旋密度，而其他原子（几乎）为零。