We work on both the theoretical and experimental aspects of high energy density (HED) science, with a particular focus on warm dense matter (WDM).

Topics:

Ab-initio simulations

we develop state-of-the-art path integral Monte Carlo (PIMC) and density functional theory (DFT) simulations to describe extreme states of matter. This includes the exploration of thermal XC-effects (DFT) and of the fermion sign problem (PIMC).

Time-dependent DFT

we develop and apply novel TD-DFT methodo­logies for the calculation of spectral properties, in particular related to x-ray Thomson scattering (XRTS).

X-ray Thomson scattering

we develop integrated modeling capabilities [xDave¹, HEART²] and model-free analysis techniques for XRTS experiments, and participate in experiments at facilities world wide [EurXFEL, LCLS, SACLA, NIF, …]

Analytic continuation

we develop novel methods [PyLIT³] for the computation of dynamic/spectral properties from quasi-exact PIMC simulation results in the imaginary-time domain.

Density response theory

we develop novel concepts for the calculation of linear and non-linear density response properties of quantum many-body systems, with a particular focus on warm dense matter.

X-ray absorption and emission spectroscopy

we work on x-ray absorption/emission experiments to study the ultrafast heating and ionization dynamics in hot dense matter.

SAXS and X-ray Imaging

We work on nano­meter-scale-sensitive small-angle X-ray scattering (SAXS) and sub-micro­meter-scale-sensitive X-ray imaging to investigate the spatiotemporal dynamics of solid-density plasmas driven by high-power laser pulses at XFEL facilities, co­vering processes from preplasma generation and ultrafast heating, ionization, and filamentation to laser-driven hydrodynamic blast-wave evolution and transient return-current-induced compression relevant to inertial confined fusion conditions.

Third-party funded projects:

ERC Starting Grant “Predicting the Extreme” (PREXTREME)

We develop new ways to deal with the notorious fermion sign problem in ab initio path integral Monte Carlo simulations of warm dense mat­ter (and other quantum degenerate Fermi systems).

DFG Heisenberg Project DO 2670/1-1

We utilize our unique combination of cutting-edge PIMC, DFT and XRTS capabilities to pursue a fundamentally improved description of warm dense matter.

EruM Data Project

“DEMOS Demokratisie­rung von Modellen”

BMFTR Project “VANLIFE”

We contribute ab-initio results for the equation-of-state of light elements for inertial fusion energy applications.

High Energy Density

We call matter with energy densities exceeding ~10¹¹ J/m³ "high energy density" matter, which corresponds to pressures above 100 GPa (= 1 million times atmospheric pressure). These states of matter can be found in the deep interiors of planets and stars as well as in many laboratory applications, e.g. the interaction of intense lasers with materials. Our division is active in various areas of this reletively new and quickly evolving field of research.

Warm Dense Matter

Warm Dense Matter, i.e. the transition regime between solids or liquids and hot plasmas is present in the interiors of many celestial bodies like planets and stars, but also plays a major role in modern laboratory applications like synthesis of new materials, intense laser-matter interaction, fusion research, and many more. Our team works towards first experiments at European XFEL equipped with HIBEF, which will allow for unprecedented insights into the dynamic properties of warm dense matter. A Helmholtz Young Investigators group is planning Day-1 WMD experiments at HIBEF. More information can be found here.

EUCALL Target Network - EuTN

In the frame of the European Cluster of Advanced Laser Light sources, the HED group is promoting a European initiative aimed at enabling high repetition rate experiments at advanced laser facilities. The goal of this initiative is to make available for the European community a sustainable infrastructure for sample supply and technical solutions for issues such as, for example, sample debris, effects of electromagnetic pulses and sample damage.

Small-Angle X-Ray Scattering – SAXS

The group has successfully applied Small-Angle X-Ray Scattering to the study of nanometer scale phenomena in plasmas generated by ultra-intense laser-matter interactions. This technique can explore feature sizes in the order of 5 nanometers, bridging the current ranges between phasecontrast imaging (~500 nm) and diffraction imaging (~ Å).