Transition-path spectra at metal surfaces

Diffusion mechanisms at both Ag and Cu metal surfaces are investigated by using the dimer method, within an embedded-atom-method approach. Hundreds of activation energies for different diffusion mechanisms are found and represented in transition-path-spectra plots. Such plots show qualitative common features in different metals (Ag and Cu) and reveal several information about the kinetic behavior of the investigated systems. The role of isolated and interacting defects in breaking diffusion-barrier degeneracy is analyzed, as well as the influence of reduced dimensions in generating new atomistic processes. A complex diffusion scenario is found, where multi-atom mechanisms appear frequently and are characterized, on average, by a high value of the frequency prefactor.