Structures and Energetics of Silver and Gold Nanoparticles

Abstract

The stability and energetics of metal nanoparticles are very important for their wide applications. Ino developed a continuous model combined with experimental parameters to study the stability of metal nanoparticles for several different crystalline structures. To provide comparable information for molecular simulation results, we re-examined Ino’s theory by using the parameters of the Sutton–Chen potential for silver and gold, respectively. Our results show that the most stable structure is icosahedron when the diameter is smaller than 2 nm, and truncated octahedron for larger nanoparticles. Static energies were then calculated for perfect crystalline structures to compare with the results by Ino’s theory, and different crystalline stabilities have been found. Nevertheless, all calculations indicate that truncated octahedron is the most stable structure at large sizes. Finally, thermodynamic effects have been demonstrated to be non-negligible by finding the thermodynamically stable structures of metal nanoparticles with the simulated annealing method. Therefore, experimentally developed metal nanoparticles do not necessarily always take the structure with the lowest potential energy given by either Ino’s theory or static energy calculations.