A5042019990- High-pressure geophysics and materials
- Quantum, superfluid, helium dynamics
- Advanced Chemical Physics Studies
- Atomic and Molecular Physics
- Astro and Planetary Science
- Geological and Geochemical Analysis
- Combustion and Detonation Processes
- Computational Physics and Python Applications
- Cold Fusion and Nuclear Reactions
- Phase Equilibria and Thermodynamics
- Spectroscopy and Quantum Chemical Studies
- nanoparticles nucleation surface interactions
- Chemical Thermodynamics and Molecular Structure
- Chemical Reactions and Isotopes
- Laser-Plasma Interactions and Diagnostics
- Energetic Materials and Combustion
- High-Velocity Impact and Material Behavior
- Superconducting Materials and Applications
University of Rostock
2018-2024
Washington State University
2018
Accurate knowledge of the properties hydrogen at high compression is crucial for astrophysics (e.g., planetary and stellar interiors, brown dwarfs, atmosphere compact stars) laboratory experiments, including inertial confinement fusion. There exists experimental data equation state, conductivity, Thomson scattering spectra. However, analysis measurements extreme pressures temperatures typically involves additional model assumptions, which makes it difficult to assess accuracy rigorously. On...
Abstract We investigate the material properties of a mixture hydrogen, helium, and oxygen representative Saturn’s interior at pressure–temperature conditions recent Saturn model (see Mankovich & Fortney) with molecular dynamics simulations based on density functional theory. Their considers demixing hydrogen helium predicts He-rich layer above diluted core. calculate thermodynamic transport discuss impact evolution structure. find significant specific heat capacity, speed sound,...
The temperature ($T$) and density ($\ensuremath{\rho}$) conditions at which hydrogen undergoes a molecular-to-atomic (MA) transition is crucial to our understanding of the gas-giant planets such as Jupiter Saturn. First-principles (FP) calculations suggest that this coincident with metallization acts catalyst for hydrogen-helium demixing, has significant consequences models planetary interiors. Prediction boundary proven be difficult using FP methods. In particular, detailed comparisons...
We used molecular dynamics simulations based on density functional theory to study the thermophysical properties of warm dense helium. The influence different exchange-correlation (XC) functionals was analyzed. calculated equation state at high pressures up several Mbar and temperatures 100 000 K in order reconstruct recent static, single shock, quasi-isentropic compression experiments. Furthermore, we dynamic electrical conductivity determined reflectivity DC conductivity. compared our...
The Kubo-Greenwood (KG) formula is often used in conjunction with Kohn-Sham (KS) density functional theory (DFT) to compute the optical conductivity, particularly for warm dense mater. For applying KG formula, all KS eigenstates and eigenvalues up an energy cutoff are required thus approach becomes expensive, especially high temperatures large systems, scaling cubically both system size temperature. Here, we develop calculate conductivity within stochastic DFT (sDFT) framework, which...
We examine the metallization of fluid helium with molecular dynamics simulations based on density functional theory. The insulator-to-metal transition is studied at densities between 1 and $22\phantom{\rule{4pt}{0ex}}\mathrm{g}/{\mathrm{cm}}^{3}$ temperatures 10 000 50 K. calculate equation state, band gap dependent temperature by using different definitions, DC conductivity, reflectivity, ionization degree for which a novel method has been proposed recently [see M. Bethkenhagen et al.,...
Accurate knowledge of the properties hydrogen at high compression is crucial for astrophysics (e.g. planetary and stellar interiors, brown dwarfs, atmosphere compact stars) laboratory experiments, including inertial confinement fusion. There exists experimental data equation state, conductivity, Thomson scattering spectra. However, analysis measurements extreme pressures temperatures typically involves additional model assumptions, which makes it difficult to assess accuracy data....
We applied two-phase simulations to directly calculate the high-pressure melting line of helium from 425 10 000 K and 15 GPa 35 TPa by using molecular dynamics based on density-functional theory. The implementation simulation method relaxation an equilibrium state was studied in detail, as well its convergence with respect particle number. performed extensive Perdew, Burke Ernzerhof van der Waals density functional exchange-correlation found almost identical results.
Abstract The nonmetal‐to‐metal transition in dense fluid helium is discussed, which has been, analogy to metallization of hydrogen, predicted as first‐order plasma phase using chemical models for the equation state and composition. However, recent ab initio simulations performed indicate that this continuous considered regime, without a density jump latent heat characteristic transition. Implications some astrophysical plasmas are discussed.