▎ 摘　　要

Structural stability and electronic structure of homogeneously arranged nitrogen-doped graphene have been investigated using first-principles calculations within the density functional theory. The structures of the homogeneously doped graphene are uniquely specified by the chiral index (n,m) inherent in each model and by the doping configurations. While the formation energy increases in proportional to the nitrogen density, there are specific arrangements for which the formation energies become lower compared to the proportional trend. Such an anomalous stabilization has been found in the honeycomb-type configuration with the chiral index (n,m) which satisfies the relation n m = 31 +2( = 0, 1, ...). This stabilization is originated from the lowering of the one-electron energy with the band gap formation, which is attributed to the decoupling of the degenerate states.