Many diffusion systems presented an anomalous fast diffusion (e.g. noble metals in lead; Zn, Pt, and Au in Si; Be in GaAs), which could be interpreted by means of the interstitial-substitutional exchange. The dissociative variant of this model, where the exchange between interstitial and substitutional configurations took place with the interplay of vacancies, was simulated using the Monte Carlo method, that permitted the avoidance drastic simplifications used to solve analytically the set of reaction-diffusion equations describing this model. The interstitial-vacancy pair (I-V), where the binding energy was considered up to the second-nearest neighbors, was considered. The results showed that the penetration profiles changed their shape from two- to three-stage profiles depending upon the magnitude of the binding energy of the pair (I-V). The variation of the impurity (or solute) correlation factor f versus the annihilation frequency of the pair (I-V) was found to be similar to that obtained analytically. The time evolution of the penetration profiles was also investigated.

Monte Carlo Calculation of Correlation Factors and Concentration Profiles for Interstitial-Substitutional Diffusion Mechanism with Impurity-Vacancy Interaction in the FCC Lattice. A.Hasnaoui, A.Menai: Physica Status Solidi B, 2002, 233[1], 158-69. See also: Computer Physics Communications, 1999, 121, 650