THEORETICAL-STUDY OF SURFACE ALLOY FORMATION THROUGH GENERATION AND ANNIHILATION OF VACANCIES

Recent STM experiments suggest that the formation of a surface alloy, when Mn is deposited on Cu(100), could be attributed to a kink-induced vacancy formation, followed by Mn incorporation through vacancy annih ilation in the step vicinity, We present an extension of the kinetic t ight-binding Ising model, which takes into account the preferential fo rmation of vacancies at the kink, their diffusion towards the centre o f the terrace and their annihilation by Mn adatoms. The jump frequenci es are obtained using molecular dynamics within the second moment appr oximation of the tight-binding scheme. The spatial distribution of inc orporated Mn and its asymmetry between the upper and lower terrace are discussed in view of the STM experiments.