Evaporation from the (1 1 0) surface of PETN

In order to provide insight into coarsening mechanisms of pentaerythritol tetranitrate (PETN), we performed kinetic Monte Carlo (KMC) simulations of evaporation from the predominantly exposed (1 1 0) surface. Our KMC simulations show that different surface structures, such as islands and straight step segments, move in very different ways during evaporation. We show that closed surface structures (e.g. islands or convex step edges) evaporate faster than open features (e.g. straight or concave step edges) due to inexhaustible sources of kink sites in their edges. From Arrhenius plots of step velocities we obtained activation energies for evaporation that are in excellent agreement with predictions from a model and recent experimental data. The effects of surface diffusion on evaporation rates are discussed within a rate theory model.