The 5-parameter Morse potential (5-MP) of the interaction between N atom and Fe surface has been constructed. The absorption and diffusion of N on Fe low index surfaces were investigated with 5-MP in detail. All critical characteristics of the system were obtained, such as adsorption site, adsorption geometry, binding energy, eigenvalues for vibration, etc. The calculated results show that N atom is located at the fourfold hollow site of the intact Fe(100) surface, and on Fe(110) surface, N atom trends to occupy quasi-3-fold site without exception. However, the most stable site on Fe(111) surface is approximate bridge site.

Key words: N-Fe system, 5-MP, surface adsorption, surface vibration, low index surface