Ag原子链的结构稳定性和磁性

采用第一性原理方法研究了Ag原子链的结构稳定性和磁学性质.在结构稳定性方面,计算了线性链、平面之字型、梯型和三条线性原子链组成的T型等链式结构.结果表明,线性原子链的结合能最小，结构最不稳定性；T型结构的结合能最大，结构最稳定.所有这些一维结构的原子间键长都小于Ag体材料的键长，表明一维下原子间的成键比体材料时更强.对Ag线性原子链的磁性计算表明，线性Ag原子链在平衡状态下并不表现出磁性,但是当原子链的原子键长被压缩了约52%时，体系可表现出铁磁性.通过Stoner判据和原子轨道相互作用图像，解释了这种磁性出现的原因. 关键词： Ag原子链 结构稳定性 磁性 从头计算

The structural stability and magnetism of Ag atomic chains

The structural stability and magnetism of Ag atomic chains are studied by the first principles calculations. The chain structures, such as the linear, zigzag, ladder and T structure which are formed by three linear chains, are studied. The results show that the linear structure is the most unstable geometry with the lowest cohesive energy. The T structure is the most stable geometry, showing the largest cohesive energy. The bond lengths in all the atomic chains studied are shorter than that in the bulk, indicating a stronger bonding strength in the atomic chains as compared with the bulk material. Besides, the study on the magnetism of Ag linear chain reveals that the linear structure could exhibit magnetism when the bond length is compressed by as large as 52%, although the equilibrium linear chain is non magnetic. By employing the Stoner criteria and the interaction picture of atomic orbitals, the reason for the possible magnetism of Ag linear chain are explained.