Preferential segregation of Pd atoms in the Ag-Pd bimetallic cluster: Density functional theory and molecular dynamics simulation

Classical molecular dynamics simulations of the coalescence between an Ag cluster composed of 135 atoms and a Pd cluster of 16 atoms were performed at 500 K. All Pd atoms penetrated into the Ag cluster and preferentially segregated at the subsurface layer. The density functional theory calculations revealed that the center site is the most stable position for Pd atoms. However, the energy barrier for further penetration of Pd atoms located at the subsurface was too high to overcome, and thus a metastable structure with Pd atoms segregated at the subsurface did not evolve.