The effects on tracer diffusion of both externally applied strains and internal strains generated by large interstitial particles dissolved in a coherent hard-sphere crystal were examined quantitatively. The molecular-dynamics method, generalized to permit elastic deformations of a system, was used to simulate the diffusion of interstitials in a binary hard-sphere solid. A tracer-diffusion response function E(k) was calculated from a tracer density-density correlation function. The associated diffusivity D was found to be independent of crystallographic orientation at long wavelengths. The simulation results were further interpreted by using a multiclass master equation to describe particle transitions and by using elasticity theory. The diffusivity obtained could be characterized very accurately by an activation entropy that was proportional to the square of the radius of an interstitial. Finally, the application of an external strain could modify the symmetry of the lattice, and the diffusion tensor associated with the deformed lattice must be modified in a manner consistent with elastodiffusion theory.

Molecular-Dynamics Study of the Effects of Strain on Interstitial Diffusion in a Hard-Sphere Model of a Binary Crystalline Solid. Rickman, J.M., Vials, J., Sekerka, R.F.: Physical Review B, 1991, 43[10], 8251-63