Overstabilization of the Metastable Structure of Isolated Ag-Pd Bimetallic Clusters

This report on the overstabilization of the metastable structure of isolated Ag-Pd catalyst composed of 135 Ag and 16 Pd atoms is based on a combination of several computational methods such as molecular dynamics, a density functional theory, transition-state calculation, and a modified basin hopping Monte Carlo simulation. With Pd atoms pinned at the metastable position up to the melting point, the overstabilization essentially originated from the systematic interaction of several factors, the high kinetic energy barrier of Pd movement, the low melting temperature of the 135Ag-16Pd cluster, the specific surface morphology, and the low solute concentration. Our results suggest that not only thermodynamics but additional kinetic or structural factors should be considered systematically in deciding the structure of bimetallic clusters for the given conditions.