Computer simulation of interstitial diffusion in disordered systems

We report on direct calculation of diffusion constant for interstitial diffusion in atomistic amorphous model when the inter-atomic potential between diffusing impurity and matrix atom is known. A new calculation method is suggested basing on Einstein equation. The simulation reveals that at low temperature the diffusion constant D for Lennard-Jones model (LJ) is three orders of magnitude lower as compared to crystalline bcc model. Furthermore, the number of interstitial site in LJ model varies for different impurity and is much less than in bcc model. In comparison with fcc model, the diffusion constant for both models is close to each other. The temperature dependence of Arrhenius plot for regular disordered lattice is also examined and discussed here.