Origin of compact triangular islands in metal-on-metal growth

The microscopic origin of compact triangular islands on close-packed surfac es is identified using kinetic Monte Carlo simulations with energy barriers obtained from density-functional calculations. In contrast to earlier acco unts, corner diffusion anisotropy is found to control the shape of compact islands at intermediate temperatures. We rationalize the correlation betwee n the orientation of dendrites grown at low temperatures and triangular isl ands grown at higher temperatures, and explain why in some systems dendrite s grow fat before turning compact.