Study of the adsorption, electronic structure and bonding of C2H4 on the FeNi(1 1 1) surface

The adsorption of C2H4 on the FeNi(1 1 1) alloy surface has been studied by ASED-MO tight binding calculations. The C2H4 molecule presents its most stable geometry with the Cdouble bond; length as m-dashC bond axis parallel to the surface along the [1, −1, 0] direction, bonded on top Fe atom and bonded along a Fe–Fe bridge site. As a consequence, the strength of the local Fe–Fe bond decreases between 37 and 62% of its original bulk value. This bond weakening is mainly due to the new C–Fe interactions however no Fe3C carbide formation is evidenced on surface. The Fe–Ni and Ni–Ni superficial bonds are only slightly modified.