The adiabatic potential energy of a H atom on a Pd3Ag(111) surface, and in its sub-surface, was obtained by using first-principles calculations based upon density functional theory. The difference between the behaviours of the H atom on Pd(111) and Pd3Ag(111) surfaces was considered by comparing the calculation results. The results showed that the potential energy value increased when the H atom was located at a site where some of the surrounding atoms were Ag atoms. In addition, the potential energy minimum and the energy barrier to the bulk area of the Pd3Ag(111) surface were lower than those of the Pd(111) surface. A decrease in these values was caused by a lattice expansion due to Ag alloying.

First Principles Study of Hydrogen Atom Adsorption and Diffusion on Pd3Ag(111) Surface and in its Subsurface. N.Ozawa, N.B.Arboleda, H.Nakanishi, H.Kasai: Surface Science, 2008, 602[4], 859-63