Thermal Evolution of Pd and Pd−Pt Clusters Supported on MgO(100)

Abstract

In this work, we performed a Monte Carlo simulation study on the thermal evolution of icosahedral Pd55, Pd43Pt12, and Pd13Pt42 clusters supported on the MgO(100) surface, using the second-moment approximation of the tight-binding potentials for the metal−metal interactions and the many-body potential energy surface for the metal−MgO(100) interaction. The potential energy surface here is obtained by fitting to ab initio calculation results (Vervisch, W.; Mottet, C.; Goniakowski, J. Phys. Rev. B 2002, 65, 245411). The solid−solid structural transformation from the icosahedral structure to the layered fcc structure is found for the Pd55, Pd43Pt12, and Pd13Pt42 clusters supported on the MgO(100) surface, determined by the changes of the total potential energies and variations of the deformation parameters. It is found that the supported Pd55, Pd43Pt12, and Pd13Pt42 clusters possess the layered epitaxial fcc structure at higher temperatures after structural transformation. In addition, the composition effect on the transition temperatures of free and MgO(100)-supported Pd−Pt bimetallic clusters is discussed.