Subproject 2: Ab initio simulations of rocky mantle materials under extreme conditions

PI: R. Redmer

The project aims at calculating the thermodynamic, magnetic, and transport properties of rock material under extreme conditions, as relevant for the interior of super- Earths: pressures up to 1 TPa and temperatures up to 20000 K. In particular, materials of the MgO-FeO-SiO2 complex will be treated. In the first funding period, simple components such as MgO and FeO as well as their binary mixtures (MgO-FeO) will be studied in detail. We use an ab initio method that calculates electronic and magnetic properties by means of density functional theory (DFT) and determines the ion dynamics with classical molecular dynamics (MD) simulations. The DFT-MD method has been proven to be very successful for the treatment of matter under extreme conditions so that it will be applied in subprojects 1–3. This consensus on theoretical methods and algorithms will lead to strong synergies within the Research Unit. The DFT calculations will be combined with the Hubbard model (DFT+U) in order to treat the strong electronic correlations in the Fe2+ ion and, thus, also in all iron-bearing alloys adequately. Structure-search algorithms will be applied to identify and investigate new high-pressure structures, in particular for binary and ternary mixtures. The material data calculated here will be applied in the modeling of extrasolar super-Earths in subproject 4 and experimentally verified in subprojects 7–9.

Phase diagram of MgO. The B1-B2 transition is predicted from DFT-MD simulations by taking into account anharmonic contributions (black line); for details, see Cebulla (2014).
Phase diagram of carbon as predicted from DFT-MD simulations. The coexistence lines between the diamond, BC8, and sc phase were determined accounting for anharmonic contributions; for details, see Schöttler (2016).

Contact PI

Prof. Dr. Ronald Redmer
Universität Rostock, Institut für Physik, 18051 Rostock
Tel. +49 (0)381 498 6910, Fax. +49 (0)381 498 6912, Emailheike.rauerdlrde