Abstract

The MINDO/SR method has been used to study electronic and bonding properties of the (100) face of a single crystai iron silicide and the oxygen adsorption on this surface. Two 24-atoms FeSi clusters were built to model the (100) face. Atomic and molecular oxygen adsorptions on the surface atoms, and other sites located above interatornic regions were calculated. For these clusters, the bonds between Fe and Si are of sp-sp type with a small direct d orbitd participation of the iron atoms. The oxygen adsorption occurs preferably over the silicon atoms and not on the iron atoms. The molecular oxygen adsorption results in a dissociative process where the dissociated oxygen atoms remain coordinated, in high extension, to silicon surface atoms.