零模超晶格类型对石墨烯纳米带金属性影响的密度泛函理论研究

Density Functional Theory Study on the Influence of Zero-mode Superlattice Types on the Metallicity of Graphene Nanoribbons

通过在石墨烯纳米带(GNR)中引入一对跳跃参数相等的零模构建金属石墨烯纳米带模型,基于密度泛函理论计算了模型的电子特性。通过改变引入的零模类型(C-C、B-B、N-N、Al-Al和P-P)对其金属度进行调控。研究表明:一对N-N零模的引入可以极大地增加GNR的金属带宽,约为引入C-C型零模金属GNR金属带宽的两倍,为本征石墨烯金属带宽的10倍。零模类型影响GNR金属带宽的原因是,引入的零模类型使GNR中形成的五元环几何构型存在差异,影响其子晶格极化损失程度,从而调控其金属度。使用零模类型为N-N的GNR为基础模型,探究纳米带的宽度对GNR金属带宽的影响,结果表明:纳米带宽度的增加不利于金属带宽的拓展,带宽扩大到某一程度时,N-N零模键断裂,变为普通N掺杂型石墨烯。

In this work,a metal GNR(graphene nanoribbon)model is constructed by introducing a pair of zero modes with equal jumping parameters into the GNR.The electronic properties of the model are calculated based on density functional theory.The metallicity can be adjusted by changing the type of zero-mode(C-C,B-B,N-N,Al-Al and P-P)introduced.Studies have shown that the introduction of a pair of N-N zero-modes can greatly broaden the metal bandwidth of GNR,which is about twice that of the introduction of C-C type zero-mode metal GNRs and ten times the bandwidth of the intrinsic graphene metal.The reason why the zero-mode type affects the metal bandwidth of graphene nanoribbons is that the introduced zero-mode type makes the five-membered ring geometry formed in the GNR differ,which affects the degree of polarization loss of its sublattice,thereby regulating its metallicity.Using graphene nanoribbons with the zero-mode type of N-N as the basic model,the effect of the width of the nanoribbon on the GNR metal bandwidth is explored,the results show that the increase in the width of the nanoribbon is not conducive to the expansion of the metal bandwidth.When the bandwidth is expanded to a certain extent,the N-N zero-mode bond broken and becomes ordinary N-doped graphene.