Computational Mechanics of Bridgmanite at High-Pressure, High-temperature and as a Function of Strain-Rate

Abstract:

It is widely accepted that bridgmanite is the most abundant mineral of the Earth’s mantle. Therefore, the convective flow and the seismic properties of the Earth’s deep mantle should depend strongly on the mechanical and physical properties of this mineral. Nowadays, atomic scale modelling of dislocation properties appears as one of the possible route to accurately infer the plastic behaviour of high pressure minerals.
In this study, we propose a theoretical modelling of dislocation glide in the easiest slip systems in MgSiO3 perovskite taking into account the influence of pressure and the effect of temperature. We focus on [100](010) and [010](100) slip systems and develop a multi scale model based on atomistic calculations to evaluate the mobility of dislocation under the conjugate action of stress and temperature and at various strain-rates. In particular, we show how numerical techniques such as Nudged Elastic Band are useful to evaluate the intermediate atomistic configurations which control lattice friction. Finally, we show that our model enables to calculate the strength of MgSiO3, either under laboratory conditions to compare with experimental data or under mantle strain rates.