REARRANGEMENTS OF BULK FACE-CENTERED-CUBIC NICKEL MODELED BY A SUTTON-CHEN POTENTIAL

Using eigenvector-following we have calculated minima, transition stat es and rearrangement mechanisms for face-centred-cubic (fcc) solids bo und by a Sutton-Chen (SC) Ni potential. Our results indicate that the divacancy mechanism is the most significant factor in the upward curva ture of the Arrhenius plot for the diffusion coefficient. We were unab le to identify any true double- or correlated-jump mechanisms in eithe r mono- or divacancy structures. The low migration energies of interst itial defects are balanced by high formation energies which preclude t hem from contributing significantly to diffusion rates. Calculations b ased upon cells containing only 100 atoms have been criticised because of the unrealistically high effective defect concentrations when comp ared with a real solid at the melting point. We compare results for ce lls containing 256 and 500 atoms and conclude that our calculated stat ionary points are actually quite well converged.