Pressure effects on self-diffusion in periclase was investigated by molecular dynamics, and the viscosity variation of lower mantle periclase was predicted by employing the Nabarro-Herring model. The self-diffusion coefficients were derived directly from recorded trajectories of atoms. The calculations were performed at 2400 to 6000K and 0 to 140GPa. The migration energy and formation energy at 0GPa were consistent with experimental data. The observed pressure dependence of self-diffusion coefficients changed from negative with increasing pressure. The behavior of self-diffusion coefficients predicted a softening of lower mantle periclase with increasing depth. A 1.3-times reduction in the viscosity (0.3K/km geothermal gradient) or 2.0-times (0.6K/km geothermal gradient) was predicted.

Pressure Effect of Self-Diffusion in Periclase (MgO) by Molecular Dynamics. Ito, Y., Toriumi, M.: Journal of Geophysical Research B, 2007, 112[4], B04206