The diffusion of sub-surface impurities such as C in Pd surfaces of (111) orientation was studied in a generalized gradient approximation which combined a pseudopotential plane wave scheme with the aim of providing a better understanding of theoretical and experimental behaviors. The stability of various sub-surface sites, the energy barriers separating them from neighboring sites, and the corresponding energy profiles were analyzed. It was found that the most stable sites were located between the first and second surface layers; in good agreement with experiment.

Migration of the Subsurface C Impurity in Pd(111). L.Gracia, M.Calatayud, J.Andrés, C.Minot, M.Salmeron: Physical Review B, 2005, 71[3], 033407 (4pp)