Simulations were used to find the likely paths of atomic migration of the Mg ion in forsterite (Mg2SiO4) and of the oxygen ion in MgSiO3 perovskite. The simulations showed that there existed two routes of Mg migration in the forsterite structure: paths between the M1 and M2 sites and between the M1 and M1 sites. In the MgSiO3-perovskite structure, some oxygen ions migrated to the next sites all together through the O1 vacant site; showing co-operative movements. The O ions were relatively mobile mainly along the b axis in the perovskite structure. Metastable sites were often present between a stable site and another stable site on atomic migration.

Ion Migration in MgSiO3-Perovskite and Olivine by Molecular Dynamics Calculations. Miyamoto, M.: Physics and Chemistry of Minerals, 1988, 15[6], 601-4