We have performed a comprehensive first-principles study of the electronic and geometric structure of a set of clean and S covered vicinal Pd surfaces of (111) and (110), namely Pd(211), Pd(331), Pd(320), and Pd(551), each having three-atom wide terraces. The trends in the multilayer relaxation patterns can generally be explained on the basis of charge smoothening which makes the vicinals of Pd(110) prone to larger and deeper relaxations in comparison to the Pd(111) counterparts. A range of adsorption energies for preferred adsorption sites for S is found on all four surfaces, with Pd(320) being the most receptive. We show that the adsorbate can have considerable effect on multilayer relaxations and registry of the substrate atoms. We discuss the nature of the S–Pd bonding and how this bonding is affected by the surface geometry and coordination. We relate the poisoning effect of S to the changes in the electronic structure of the substrate atoms.

• Received 10 July 2002

DOI:https://doi.org/10.1103/PhysRevB.67.165415