Diffusion of molecules in and on solid substrates often occurs as a series of hops between neighboring binding sites, or potential-energy minima. Simulation of this type of transport with molecular dynamics becomes challenging because the time between hops often exceeds times that can typically be probed with this computational technique. In this paper, we discuss a new method, which extends the time scale in molecular-dynamics simulations, while retaining nearly precise dynamic detail. A simple two-dimensional model has been used to explore the algorithm in detail. We also discuss the extension of the method to more complicated system, involving the diffusion of a Ag adatom on the AE (001) surface.