Abstract: In this paper, two kinds of appropriate cluster model Fe_5S and Fe_9S are chosen for the chemisorption system of C(2×2)S/Fe(001), The electronic structure of these two clusters, the characterics of chemisorption bonding and the picture of adsorption interaction were sutdied using SCF-X_α-MS method. Results show that adsorption of sulfur on Fe(001) single crystal surface has strong Iocal effect and sulfer 3P_x, 3P_y orbitals hybridize with the first layer iron 3d_(xz), 3d_(yz), and sulfur, 3P_z may interact with a second layer iron 4s and 3d_z2. The optimized chemisorption geomtries are in fair agreement with ARPEFS result of C(2×2)S/Fe(001) by X.S.Zhang et al.

Key words: Chemisorption system of C(2×2)S/Fe(001), Appropriate cluster model Fe₅S and Fe₉S, SCF-X_a-MS method