/graphene*

We proposed a new unfolding scheme to analyze energy spectra of complex large-scale systems of each subsystem with distinct periodicity. To treat the super periodicity in materials coming from the stacks of different materials on the basis of the density-functional calculations, we usually use the supercell scheme. However, as a drawback of the supercell scheme, electronic bands are folded into the small supercell Brillouin zones (BZ) making it difficult to analyze the band structure and compare it with ARPES spectra. Band unfolding method is efficient for such cases. However, considering twisted bilayer graphene (tBLG) and MoS₂/graphene as examples, we first show that the conventional unfolding scheme in the past using a single primitive-cell representation causes serious problems in analyses of the energy spectra. We then introduce our multi-space representation scheme in the unfolding method and clarify its validity for our target systems.

[1] Hirofumi Nishi, et al, Phys. Rev. B 95, 085420 (2017).
[2] Yu-ichiro Matsushita, et al, arXiv:1706.05921 (2017).
[3] Taichi Kosugi, et al, to be published in J. Phys. Soc. Jpn. (2017).