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Eye catcher

Non-Equilibrium Warm Dense Matter

Research on properties of matter as in the centre of planets or stars, created by short- and long pulse lasers, x-rays, ion or electron beams, in diamond anvil cells or for fusion energy production.

 

Bragg Non-thermal

Laser irradiation of metals creates non-equilibrium states with high energy electrons. The relaxation in the system and the coupling to the phonons is a complicated process that sometimes is modelled within a two-temperature model. We (R. Ernstorfer and colleagues from FHI Berlin) found that a much better description is given by including the non-thermal behaviour of the phonons.

 

Shock-compressed carbon changes phase from graphite to diamond. Under certain conditions, hexagonal diamond -lonsdaleite- can be produced. Lonsdaleite is a metastable phase of carbon featuring a crystal lattice structure in between graphite and diamond. Calculations predict lonsdaleite to be harder than diamond. Naturally occuring londsaleite is possibly generated in meteorite impacts. A collaboration under principal investigator Dominik Kraus (HZDR, University Berkeley) has just published these new insights. There is a nice summary here.

warm dense Diamond warm dense carbon warm dense Lonsdaleite

Gitter- und Elektronenstruktur in warmem Diamant bei p=130GPa (links), in warmem Lonsdaleite bei p=200GPa (mitte) und in flüssigem Kohlenstoff bei p=150GPa (rechts).

 

This video showcases recent work done in collaboration with SIMES at SLAC in Stanford investigating the structure of warm dense aluminium at megabar pressures.

We are using first principle simulations like density functional molecular dynamics and quantum statistical Green's function methods to describe new and exotic states of matter in equilibrium and non-equilibrium and during various relaxation processes. We give predictions for x-ray spectra that may be obtained by scattering experiments.

molecular hydrogen metallic hydrogen warm dense aluminium

Molecular hydrogen as in Jupiter's outer mantle, warm dense aluminium created by laser generated shock waves, metallic hydrogen as in Jupiters core.