Bulletin of the American Physical Society
65th Annual Meeting of the APS Division of Plasma Physics
Monday–Friday, October 30–November 3 2023; Denver, Colorado
Session NI01: Invited: WDM & HED Materials PhysicsInvited Session
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Chair: Nicholas Hartley, SLAC - Natl Accelerator Lab Room: Plaza F |
Wednesday, November 1, 2023 9:30AM - 10:00AM |
NI01.00001: A universal density functional theory for ab-initio electronic structure and dynamics across the warm dense matter regime Invited Speaker: Alexander J White .Traditional Kohn-Sham density functional theory (KS-DFT) calculations quickly become intractable in much of the warm dense matter (WDM) regime due to a cubic scaling of the computational complexity with both temperature and system size. Orbital-Free (OF-) DFT methods have been traditionally been a more approximate theoretical alternative to KS-DFT. Recently developed stochastic KS-DFT (sDFT) methods provides an algorithmic alternative to KS-DFT. The sDFT method scales linearly with system size and inversely with temperature. This is promising for WDM, but the pre-factors make the method only practical for hot-dense plasmas, or extremely large systems. We have developed universal mixed-deterministic-stochastic DFT (mDFT) which can capture the best of both approaches.[1] This method generalizes to time-dependent-DFT for electron response as well as quantum molecular dynamics. [2] |
Wednesday, November 1, 2023 10:00AM - 10:30AM |
NI01.00002: Thermodynamic and dynamic properties of warm dense hydrogen revisited Invited Speaker: Jan Vorberger .Accurate knowledge of the properties of hydrogen at high compression are crucial for astrophysics and laboratory experiments, including inertial confinement fusion. Today there exist extensive collections of data originating from path integral Monte Carlo (PIMC) simulations [1, 2], DFT, chemical models and combinations thereof [3]. However, each of these methods has severe limitations rendering the accuracy of the hydrogen data unclear. This has become particularly evident when the first exact PIMC simulation results for the model of the uniform electron gas (UEG) became available [4] which revealed surprising deviations of restricted PIMC results. In the mean time extensive thermodynamic data for the UEG have been reported [5], and the simulations have been extended to dynamic properties, including the the dynamic structure factor [6]. Here, we present an overview on the application of our improved PIMC simulations [5] to partially ionized warm dense hydrogen, taking advantage of a further improvement originating from a transition to the grand ensemble [7]. The thermodynamic results allow us to benchmark earlier simulations and models and make reliable predictions for experiments. Moreover we present data for the momentum distribution. Finally, the roton-type minimum of the plasmon dispersion that was previously reported for the UEG [6,8], is confirmed for hydrogen as well and parameters for an experimental observation are presented [9]. |
Wednesday, November 1, 2023 10:30AM - 11:00AM |
NI01.00003: Thermal transport in warm dense matter revealed by refraction-enhanced x-ray radiography with a deep-neural-network analysis Invited Speaker: Sheng Jiang Transport properties of high energy density matter affect the evolution of many systems, ranging from the Earth's core to the inertial confinement fusion (ICF) capsules. Large uncertainties of these properties are present in the warm dense matter (WDM) regime where both plasma and condensed matter models become invalid. I will present the measurement of thermal conductivity of CH and Be in WDM using x-ray differential heating and time-resolved refraction-enhanced radiography. A novel technique with a deep neural network has been developed to retrieve the detailed density profiles. Multiple observables, including wave propagation and refractive features, enable simultaneous constraints on density, temperature, and thermal conductivity. |
Wednesday, November 1, 2023 11:00AM - 11:30AM |
NI01.00004: Insulator-to-Conductor Transition in Warm Dense Neon Invited Speaker: Grigoriy Tabak In contrast to the high-density behavior of most materials, the band gap of neon is predicted to increase with density at a wide range of conditions in both solid and fluid states [1-2]. We combine static and dynamic compression to study fluid Ne at densities up to ~6.5 g/cm3 and temperatures approaching ~100,000 K. We observe a novel trend in the reflectivity of shocked Ne, which indicates that at these conditions, the reflectivity and conductivity of Ne decrease with increasing density, supporting the band gap prediction. The results suggest that Ne remains insulating in the interiors of giant planets such as Jupiter and showcase the exotic material properties that can emerge in the warm dense matter regime. This material is based upon work supported by the Department of Energy National Nuclear Security Administration under Award Number DE-NA0003856. |
Wednesday, November 1, 2023 11:30AM - 12:00PM |
NI01.00005: Multi-platform static and dynamic compression and complete EOS modeling of ultra-wide bandgap semiconductor Ga2O3 Invited Speaker: Pat Kalita Ga2O3 is a transparent semiconducting oxide with an ultra-large band gap. Its multiple low-symmetry |
Wednesday, November 1, 2023 12:00PM - 12:30PM |
NI01.00006: Sound speed and Gruneisen parameter for iron shock compressed to 3 teraPascals Invited Speaker: Margaret F Huff With thousands of extrasolar planets recently discovered, there is an urgent need for accurate structure and evolution models of planets. The iron equation of state (EOS) at terapascal (TPa) pressures is required to model the core of rocky planets and heavy elements in gas giants. This paper presents the first sound speed and Gruneisen parameter data for fluid iron compressed to 3 TPa (30 million atmospheres) and 20 g/cm3 on the Hugoniot. Both the sound speed and Gruneisen parameter are derivatives of the EOS, and thus tightly constrain the contours of the EOS surface. The sound speed data are systematically lower than expected from a simple extrapolation of previous data. The Gruneisen parameter shows a 30% drop at pressures and temperatures above the melt transition. Furthermore, while some models compare well with either the sound speed or Gruneisen parameter, none of today’s state-of-the-art models can explain both sets of data. Thus these new data will provide pivotal benchmarks for both future theoretical EOSs of warm dense iron and modeling planetary states and processes. |
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