Molecular dynamics simulations based upon ab initio interatomic potentials were used to study the kinetics and mechanisms of interdiffusion in MgSiO3 and Mg2SiO4 melts. The diffusion coefficients in the presence of a concentration gradient were lower than the self-diffusion coefficients, due to the requirements of local charge-balance within the system. Extrapolations of Mg2+ diffusion coefficients, obtained at 500 to 3000K, to geologically relevant temperatures were reasonably accurate as compared with experimental Mg2+ diffusion coefficients in a compositionally similar system. A significant system-size effect was also observed on the rates of diffusion obtained from the molecular dynamics simulations. The diffusion mechanisms involved the movement of individual Mg2+ and O2- ions and anionic [SiOn](4-2n) complexes for both self-diffusion and interdiffusion.

Molecular Dynamics Simulations of Interdiffusion in MgSiO3-Mg2SiO4 Melts. Kubicki, J.D., Lasaga, A.C.: Physics and Chemistry of Minerals, 1993, 20[4], 255-62