The
understanding of atomic adsorption on a solid surface is essential to
understand the fundamental issue of chemical interaction at the
hetero-junctions, formed by two metals. With an aim to compare the
adsorption behavior between finite size cluster and extended surface, M
atom (M = Ni, Pd, Pt) interaction with Agn/Aun(n=
3, 6) clusters and periodic slab of Ag(111)/Au(111) surfaces is
investigated theoretically. All calculations are performed using
plane-wave pseudo-potential approach under the spin-polarized density
functional theory including the spin –orbit coupling term. The results
show that the interaction of M atom with small clusters is primarily
governed by the relative strength of MAg/Au vs. AgAg/AuAu bonds. The
stronger interaction follows rearrangement of the host cluster. For the
periodic slab, M atom prefers to adsorb on the fcc site with small local
distortion. Due to variation in the strength of interaction and amount
of distortion, the cluster and periodic slab differs in absolute
adsorption energy values. Further a comparative analysis of chemical
bonding through electronic density of state (EDOS) and orbital
decomposed charge distribution infers that interaction of Ni/Pd/Pt with
gold substrate is stronger than silver substrate.