Tungsten migration energy barriers for surface diffusion: a parameterization for KMC simulations

We have calculated the migration barriers for surface diffusion on tungsten. Our results form a self-sufficient parameterisation for kinetic Monte Carlo simulations of arbitrarily rough atomic tungsten surfaces, as well as nanostructures such as nanotips and nanoclusters. The parameterisation includes first- and second-nearest neighbour atom jump processes, as well as a third-nearest neighbour exchange process. The migration energy barriers of all processes are calculated with the nudged elastic band method. The same attempt frequency for all processes is found sufficient and the value is fitted to molecular dynamics simulations. The model is validated by correctly simulating with kinetic Monte Carlo the energetically favourable W nanocluster shapes, in good agreement with molecular dynamics simulations. (paper)