(color online) (a) Band structure and the corresponding density of states (DOS) for 6-ED-ZGNR. The Fermi levels in the band structure and DOS are both set to be zero, and are indicated by the horizontal green line. (b) Partial densities of state (PDOSs) for 6-ED-ZGNR, where the Fermi level set to be zero is indicated by the vertical green line. The black, blue, magenta and orange lines denote TDOSs of zigzag cusps, quasi-edge and phenyl atoms, respectively.