Diffusion in minerals of the Earth's lower mantle: constraining rheology from first principles

摘要: Absolute di�ffusion rates in minerals of the Earth's lower mantle are calculated from �first principles using density functional theory. The agreement with available experimental data is excellent and provides con�fidence in predicting di�ffusivities regions inaccessible to current techniques. I have calculated di�ffusivity all constituting species ferro-periclase ((Fe,Mg)O), (Fe,Mg)SiO3 perovskite MgSiO3 post-perovskite. This enables me put tight constraints on viscosity of the mantle, and, particular, post-perovskite for which no available. �find that deforming in diff�usion creep can readily reproduce viscosity profi�le has been inferred from inversion modelling. also show postperovskite is either much stiff�er (if deforming creep) or up to four orders magnitude weaker than dislocation creep). leads a new interpretation sharp seismic reflector in the lowermost known as D00, onset sudden rheological transition generation mineral texture therewith. Finally, I also pressure induced high-to-low-spin transition iron ferro-periclase and negligible e�ffect rheology mantle.