Models for adatom diffusion on fcc(001) metal surfaces

We present a class of models that describe self diffusion on several fcc(001) metal substrates within a common framework. The models are found to apply well for Cu(001), Ag(001), Au(001), Ni(001) and Pd(001).For each of these metals the models can be used to estimate the activation energy of any diffusion process using a few basic parameters which may be obtained from experiments, ab-initio or semi-empirical calculations. To demonstrate the approach, the parameters of the models are optimized to describe self-diffusion on the (001) surface, by comparing the energy barriers to a full set of barriers obtained from semi-empirical potentials via the embedded atom method (EAM). It is found that these models with at most four parameters,provide a good description of the full landscape of hopping energy barriers on FCC(001) surfaces. The main features of the diffusion processes revealed by EAM calculations are quantitatively reproducible by the models.