FeS_2(100)表面原子几何与电子结构的理论研究

Theoretical study on the geometry and the electronic structure of FeS_2(100) surface

采用密度泛函理论研究了FeS2 (10 0 )表面原子几何与电子结构 .理论计算结果表明 :FeS2 (10 0 )表面无弛豫、无重构 ,是体相原子几何的自然终止 .与体相电子结构相比 ,FeS2 (10 0 )表面电子特性明显不同 ,禁带中央产生新的表面态 ,且表面态局域性强 ,主要由Fe原子的 3d分波贡献 .配位场理论定性分析表明 :FeS2 (10 0 )完整晶面表面态产生机制是Fe原子的配位数减少。

The geometry and the electronic structure of FeS2 (100) surface is studied using the density-functional theory (DFT) method. The (100) surface is very stable, does not give any significant geometric relaxation and can be regarded as simple termination of the bulk structure along a plane of cleaved Fe-S bunds. The,electronic structure at the (100) surface appears rather different from the bulk electronic structure. The electronic structure of FcS(2) (100) surface is characterized by surface states in the forbidden zone. Die highest occupied and the lowest unoccupied states are localized at surface Fe sites. According to ligand field theory, the existence of a new type of surface states in the forbidden zone resulting from symmetry reduction of the Fe coordination is deduced.