Iron under Extreme Conditions
14th June 2017, PHYSIKALISCHES KOLLOQUIUM, Hörsaal MC 122, Campus Duisburg, Universität Duisburg-Essen
Start: 14th June 2017 01:00 p.m.
End: 14th June 2017 03:00 p.m.
Prof. Dr. Ronald Cohen, Ludwig-Maximilians-University Munich, Department of Earth and Environmental Sciences
Fakultät für Physik, Universität Duisburg-Essen
We are performing first-principles studies of transport properties, equations of state, and phase equilibrium in solid and fluid iron and iron-hydrogen mixtures under extreme conditions using density functional theory (DFT) and dynamical mean field theory (DMFT). For transport proper-ties we are using a combination of density-functional perturbation theory (DFPT) with the ABINIT package, first-principles molecular dynamics (FPMD) with QUANTUM ESPRESSO, KKR-CPA, and DMFT. We find that lower pressure (100 GPa) results agree well with experiments, but deviate with increasing pressure and temperatures, suggesting difficulties in extreme condition experiments and with experimental extrapolations. We get good agreement with other theoretical studied when making the same approximations. We will discuss the effects of including saturation effects and higher-order effects that come into play at high temperatures. We are also studying equations of state of Fe-H fluids at extreme conditions to understand giant planetary cores includeing Jupiter and exoplanets. We have performed FPMD for Fe-H systems within DFT up to 30,000 K and 4 TPa. We find complete miscibility in Fe-H fluids at extreme conditions, and non-ideaility is rather small. Simulations for pure iron at high P and T are also being performed to help interpret experiments at the National Ignition Facility (NIF) including ramp compression in the solid phase to very high P and T. This work is supported by the European Research Council (ERC) advanced grant ToMCaT, Theory of Mantle, Core, and Technological Materials.