First-principles study of inter nitrogen interaction energy of Cu(1 0 0)–c(2×2)N surface

Cu(1 0 0)–c(2×2)N surface was studied by a first-principles calculation. The optimized atomic structure of Cu(1 0 0)–c(2×2)N surface had the fourfold symmetry. The calculated diffusion path and the barrier of an isolated nitrogen atom on Cu(1 0 0) surface was the path through the bridge site and 1.5–1.7 eV, respectively. The scanning tunneling microscope (STM) image of Cu(1 0 0)–c(2×2)N surface was simulated in consistent with an STM experiment. Effective interaction energy on this surface among nitrogen atoms was calculated and was found to be attractive one as suggested by experiments.