Vacancy and interstitial diffusion in bcc-Fe

Using molecular dynamics and long ranged pair potential the vacancy diffusion has been studied in bcc-Fe. The diffusion coefficients were calculated using mean square displacements and jump frequencies. It was confirmed that vacancy diffusion is described by random walk theory. Interstitial diffusion has been studied using the above mentioned potential and the short ranged Johnson potential. The potentials describe different stability of the interstitial atoms. Nevertheless, the results of the diffusion study are qualitatively similar. For low temperature the interstitial migrates one-dimensionally via crowdion mechanism, and for high temperature the diffusion is three-dimensional via the dumb-bell mechanism.