Size- and shape-dependent energetics of nanocrystal interfaces: experiment and simulation.

We study the interface energetics of Ag nanocrystals on a H-passivated Si(111) surface by a transmission electron microscopy experiment and molecular dynamics simulations. The annealed nanocrystals are oriented with Ag(111)||Si(111). Azimuthally, epitaxy is preferred for nanocrystals with an interface larger than a coincident-site-lattice (CSL) cell. The equilibrium orientation, or interface energy minimum, depends on the interface size and shape. For interfaces approaching a CSL cell in size ( approximately 2 nm nanocrystals), fluctuations of a single atom at an interface can lead to large variations in nanocrystal orientations.