非近邻跳跃对扶手椅型石墨烯纳米带电子结构的影响

Effect of the non-nearest-neighbor hopping on the electronic structure of armchair graphene nanoribbons

根据π电子的紧束缚模型,将电子的次近邻和第三近邻跳跃能考虑在内,得到扶手椅型石墨烯纳米带(AGRNs)能带结构的解析解.讨论了由次近邻和第三近邻电子跳跃引起的能带和能隙变化,发现次近邻和第三近邻跳跃分别对带隙产生增大和减小的影响.比较了边界弛豫与非近邻跳跃之间的互相竞争关系.当纳米带的宽度n为奇数时,二维石墨面的紧束缚模型中所固有的vanHove奇异性表现为AGRNs中的无色散带.当AGRNs宽度增加时,能谱趋向于二维石墨烯时的能谱结构.

Based on the tight-binding model,the non-nearest-neighbor hopping terms of electrons are taken into account and the energy spectra of the armchair graphene nanoribbons（AGRNs） are given analytically. The changes of the energy band and the gap with the non-nearest-neighbor terms are discussed. The results show that the next-nearest-neighbor term can increase the gap and the third-nearest-neighbor term can narrow the gap. The competition relationship between the edge relaxation and the non-neighbor term is compared. When the width n is odd,the van Hove singularity from graphene sheets leads to the dispersion-less band. When the width of AGRNs goes to infinity,the spectrum of AGRNs tends to that of graphene sheets.