First-principles study of Pd-V surface alloys I. Electronic structure of clean surfaces

We investigate the influence of vanadium impurities on the geometric and electronic properties of palladium (111) surfaces using ab initio density functional calculations. Our calculations are based on projector augmented wave potentials in a plane wave basis set and the Perdew-Wang generalised gradient approximation for the exchange-correlation functional. Single-layer vanadium concentrations range from c = 1 to 1 in the surface and subsurface layers. The surface is simulated by repeated slabs consisting of four to eight layers of metal and separated by several layers of vacuum. Impurities are introduced on one side of the slab only where the atoms of the topmost layers are allowed to fully relax. Regarding the electronic structure we investigate the local and partial densities of states (LDOS and PDOS respectively) of the surface atoms of different alloys as well as the LDOS of vanadium. The local effects of alloying on the d-bands of the neighbouring atoms are discussed. Finally we examine surface states of highly concentrated PdN surface and subsurface alloys. The findings are a first step towards the understanding of the chemical reactivity of surface alloys consisting of a late and an early transition metal. (C) 2001 Elsevier Science B.V. All rights reserved.