Electronic interactions in bimetallic bonding: molecular-orbital study of Pd/Al(111) andAu/Al(111)

摘要: The interaction of Pd and Au with Al(111) has been studied using ab initio SCF calculations cluster models. bonding mechanism ofPd on involves electron transfer from the valence d orbitals admetals toward substrate, a compensating charge substrate into (s,p) admetals. behaves as net donor (Pdδ+, δ≈0.25e), while acts acceptor (Auδ−, δ≈0.10e). In spite this difference in direction transfer, both show shifts higher binding energy their bands, consequence losses d-electron population. electronic perturbations observed after to Al are large those found for bonded early-transition metals, much bigger than when is late-transition metals. Similar trends seen adatoms. general, reduction Pd(4d) or Au(5d) population increases fraction empty states band rises. Changes chemical properties overlayers (positive binding-energy core levels admetal, decrease work function CO-desorption temperature Pd) can be explained terms simple model that → (5s,5p) rehybridization.