Pressure effect of self-diffusion in periclase (MgO) by molecular dynamics

[ 1] Pressure effect of self-diffusion in periclase (MgO) was investigated by molecular dynamics ( MD), and viscosity variation of lower mantle periclase was predicted by employing the Nabarro-Herring model. Self-diffusion coefficients were derived directly from recorded trajectories of atoms. The MD calculations were performed at 2400 - 6000 K and 0 - 140 GPa. Migration energy (H-m*) and formation energy (H-f*) of ordinary pressure ( 0 GPa) are consistent with experimental data. Observed pressure dependence of self-diffusion coefficients was turned from negative with increasing pressure. The behavior of self-diffusion coefficients predicts softening of lower mantle periclase with increasing depth. We predict 1.3 times reduction of the viscosity (0.3 K/km geothermal gradient) or 2.0 times (0.6 K/km geothermal gradient).