Density functional theory is used to investigate vacancies at or below the (111) surface of palladium and in the bulk. An accurate nonlocal pseudopotential for Pd based on relativistic all-electron calculations is employed. The interaction of the vacancy, a point defect, with a surface, a planar defect, is investigated. Also studied is the interaction between electronic structure and lattice structure around the vacancy. The vacancy-formation energy increases with the depth of the vacancy and with decreasing vacancy concentration. The ions surrounding a vacancy relax slightly into it, and the amount of relaxation decreases as vacancy depth is increased or as vacancy concentration is decreased. The primary electronic effects of the vacancy are a spillout of electrons into it and a strengthening of the bonds between the neighboring atoms that accompanies the inward relaxation.

• Received 30 August 2002

DOI:https://doi.org/10.1103/PhysRevB.67.085403