▎ 摘　　要

By using the first-principles method based on the density-functional theory, electronic properties of graphene nanoribbons punched with periodic nanoholes (GNRPNHs) are studied systematically. It has been shown that the zigzag-edge GNRPNH at the nonmagnetic state is always metal regardless of neck widths, but its metallic properties is obviously weakened due to nanohole effects, and at the anti-ferromagnetic states, its spin degeneracy still remains and the energy gap has only a smaller change. While for armchair-edge GNRPNHs, the situations are complicated. As compared with the perfect AGNRs, their band gaps become smaller or larger depending on the ribbon widths satisfying W = 3p + 1, 3p, or 3p - 1. The analysis in depth shows that underlying origins are closely related to the width and edge shape (zigzag or armchair) of the neck subprime nanoribbon and edge subprime nanoribbon, which leads to the different quantum confinement effect. And also shown is the phenomenon of the odd-even oscillation for the band gap with the change of the neck width. These findings presented here provide theoretical references for experimentally punching desirable periodic nanoholes on the graphene nanoribbons to meet the special characteristics requirements of nanodevices. (C) 2013 AIP Publishing LLC.