Thermodynamic properties and stability field of MgSiO₃ post-perovskite

A high-pressure phase transition in iron free MgSiO₃ perovskite (pv), the most abundant Earth forming mineral phase, was discovered and reported in 2003-2004. A subsequent dissociation transition in the newly found polymorph was predicted in 2006. Here, we summarize our theoretical and computational studies of these phase transitions and of the physical properties of the newly found postperovskite (ppv) and post-ppv phases. Our approach is based on density functional theory, on the plane-wave pseudopotential method, and on quasiharmonic free energy computations. We focus here on the structural, vibrational, and thermodynamic properties, and on the stability field of the ppv phase. The predicted Clapeyron slope of the ppv transition and several properties of the ppv phase strongly suggest that this is an important candidate for a primary constituent in D″. We also review the post-ppv transition and the properties of the resulting aggregate. They are important for modeling and advancing our understanding of the mantle of terrestrial exoplanets and of the gas giants’ cores.