Low-temperature shape relaxation of two-dimensional islands by edge diffusion

We present a precise microscopic description of the limiting step for low-t emperature shape relaxation of two-dimensional islands in which activated d iffusion of particles along the boundary is the only mechanism of transport allowed. In particular, we are able to explain why the system is driven ir reversibly towards equilibrium. Based on this description, we present a sch eme for calculating the duration of the limiting step at each stage of the relaxation process. Finally, we calculate numerically the total relaxation time as predicted by our results and compare it with simulations of the rel axation process.