Ostwald ripening of close-packed and honeycomb islands during coadsorption

To mimic the self-assembly of hexagonally shaped molecules such as cyanuric acid and melamine, we present Monte Carlo simulations of the growth of close-packed and honeycomb islands during adsorption and coadsorption of A and B particles on a triangular lattice. Each particle occupies a single site and is characterized by its orientation on the lattice. The orientation is changed by rotation by 60°, so that the rotation by 120° does not change the Hamiltonian. The model predicts slow or nearly negligible island growth at t⩽10³ Monte Carlo steps (MCSs) and then faster growth. On the late stage (10⁵⩽t⩽10⁶ MCSs), the growth exponent is found to be 0.28–0.30 in the case of adsorption of particles of one type and 0.24–0.29 in the case of coadsorption. These values are somewhat or appreciably lower than the Lifshitz-Slyozov exponent x=1∕3.