Nonhomogeneous surface premelting of Au nanoparticles.

A reversible nonhomogeneous surface premelting of Au nanoparticles is demonstrated through molecular dynamics simulations. With increasing temperature, liquid-like atoms first appear at some vertices and edges of surface facets, then small liquid regions grow and, at temperatures close to the particle melting temperature, most of the remaining solid-like surface atoms reside on {111} planes which are the most stable against surface premelting. The appearance of a contiguous liquid layer (complete surface premelting) is size dependent and is not observed in very small nanoparticles.