Modeling the Diffusive Motion of Large Organic Molecules on Insulating Surfaces

Abstract

We show that the overall structure and flexibility of an organic molecule has a profound effect on the mechanism of diffusion and the effective diffusion rate on a surface. Calculations were performed to model the diffusion of a set of large organic molecules with polar binding groups on the perfect TiO2 (110) surface. These simulations involved determining the accessible states of the molecule surface system and the energy barriers that separate them using realistic atomistic simulations employing a set of specifically developed potentials. With the complete set of accessible states and energy barriers for each molecule, we then performed kinetic Monte Carlo simulations to determine the mechanisms of diffusion and the effective diffusion rates of the molecules. These calculations suggest ways in which the mobility of large molecules on surfaces can be controlled through careful design of the molecular structure.