Dodecagonal bilayer graphene quasicrystal and its approximants  

作　　者：Guodong Yu Zewen Wu Zhen Zhan Mikhail I.Katsnelson Shengjun Yuan 

机构地区：[1]Key Laboratory of Artificial Micro-and Nano-structures of Ministry of Education and School of Physics and Technology,Wuhan University,Wuhan 430072,China [2]Institute for Molecules and Materials,Radboud University,Heijendaalseweg 135,NL-6525 AJ Nijmegen,Netherlands

出　　处：《npj Computational Materials》2019年第1期73-82,共10页计算材料学（英文）

基　　金：This work is supported by the National Key R&D Program of China(Grant No.2018FYA0305800);China Postdoctoral Science Foundation(Grant No.2018M632902);MIK acknowledges a support by the JTC-FLAGERA Project GRANSPORT.

摘　　要：Dodecagonal bilayer graphene quasicrystal has 12-fold rotational order but lacks translational symmetry which prevents the application of band theory.In this paper,we study the electronic and optical properties of graphene quasicrystal with large-scale tight-binding calculations involving more than ten million atoms.We propose a series of periodic approximants which reproduce accurately the properties of quasicrystal within a finite unit cell.By utilizing the band-unfolding method on the smallest approximant with only 2702 atoms,the effective band structure of graphene quasicrystal is derived.The features,such as the emergence of new Dirac points(especially the mirrored ones),the band gap at M point and the Fermi velocity are all in agreement with recent experiments.The properties of quasicrystal states are identified in the Landau level spectrum and optical excitations.Importantly,our results show that the lattice mismatch is the dominant factor determining the accuracy of layered approximants.The proposed approximants can be used directly for other layered materials in honeycomb lattice,and the design principles can be applied for any quasi-periodic incommensurate structures.

关 键 词：theory. LAYERED PERIODIC 

分 类 号：O24[理学—计算数学]