Cu-Co合金纳米线稳定性和电子特性的第一性原理研究

First-principles Study on the Structure Stability and Electronic Property of Cu-Co Alloyed Nanowires

基于密度泛函理论框架下的第一性原理计算,系统地研究了轴向应力作用下均匀交替结构和非均匀二聚体结构Cu-Co合金单原子链的结构稳定性、磁性和电子结构。Cu-Co合金原子链内聚能在较大原子间距范围内均小于相应纯Cu原子链的内聚能,因此合金原子链的稳定性较高。非均匀Cu-Co合金原子链中易于形成Co2二聚体,使得合金原子链轴向电荷密度和原子间距出现非均匀分布,从而导致轴向应力拉伸作用下原子链在Cu-Cu键处过早断裂。而轴向应力作用下的均匀交替结构Cu-Co合金原子链在较大的原子间距范围内能够稳定存在。电子结构的分析表明Cu原子和Co原子间的轨道杂化导致了Cu-Co合金原子链的高稳定性。

By using first-principles calculations based on density-functional theory,the structure stability,magnetic properties and electronic structure of uniformly and nonuniformly alloyed Cu-Co monoatomic chains have been systematically investigated.The effect of elastic stretching/contraction deformations on the stability and electronic properties of alloyed Cu-Co atomic chains has also been studied. The cohesive energy per atom of Cu-Co atomic chain is lower than that for the corresponding ideal Cu atomic chain in the entire average interatomic distance. Thus,the alloyed Cu-Co atomic chain is more stable than the corresponding ideal Cu nanowire. It is established that Co dimers are easily formed in the nonuniformly alloyed Cu-Co atomic chain. The formation of Co2 dimers results in a nonuniformly distribution of the electron density and interatomic distances along the wire direction and leads to accelerated rupture of the wire between Cu atoms under stretching. While the uniformly alloyed Cu-Co atomic chain composed of regularly alternating Cu and Co atoms is stable under stretching up to large interatomic distances. The electronic structure reveale that strong hybridization between the Cu and Co states is responsible for the high stability of alloyed Cu-Co nanowire.