Bulletin of the American Physical Society
APS March Meeting 2019
Volume 64, Number 2
Monday–Friday, March 4–8, 2019; Boston, Massachusetts
Session V17: Matter in Extreme Environments: Warm Dense MatterFocus
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Sponsoring Units: DCOMP Chair: Paul Loubeyre, CEA de Bruyeres-le-Chatel Room: BCEC 156A |
Thursday, March 7, 2019 2:30PM - 3:06PM |
V17.00001: Modeling Materials at Extreme Conditions for High Energy-Density Science Invited Speaker: Stephanie Hansen Modern High Energy-Density experimental facilities study inertial confinement fusion, laboratory astrophysics, and extreme states of matter by compressing energy in space and time to produce hot, dense, and strongly coupled plasmas. In such extreme environments, changes in electronic and ionic structure impact the material equation-of-state, transport properties, and observable signatures that inform both hydrodynamic simulations and interpretations of experimental data. This talk will survey experimental programs in HED science and describe an ongoing effort to develop a highly constrained, fully self-consistent atomic-scale model of material at extreme conditions. Generating equations of state, transport properties (thermal and electrical conductivities, opacities, stopping powers) and diagnostic signatures (X-ray Thomson scattering, spectroscopic line shifts and broadening) from a single, consistent core model helps to constrain simulations and improve the reliability of data interpretation from complex experiments. |
Thursday, March 7, 2019 3:06PM - 3:18PM |
V17.00002: A Stochastic approach to thermal DFT Yael Cytter, Daniel Neuhauser, Eran Rabani, Roi Baer Despite progress in observational astronomy, some elements such as the internal composition of planets are still not well-understood. A root cause is our limited understanding of matter under extreme conditions (MEC) - pressures in the GPa-TPa range and temperatures (T) up to 105 K. Due to the difficulty in preparing MECs, the experimental input is limited, and ab initio calculations are sometimes the only source of information. The Kohn-Sham density functional theory (KS-DFT) seems as a reliable and useful tool for obtaining information on MEC. Calculations in finite temperatures, however, are expensive due to the large number of fractionally occupied KS orbitals involved. A stochastic method developed recently[1],[2], appears to be a fitting approach to this problem. By performing a stochastic trace, the KS Hamiltonian is directly obtained from the density, resulting in a scaling of O(T-1). |
Thursday, March 7, 2019 3:18PM - 3:30PM |
V17.00003: ABSTRACT WITHDRAWN
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Thursday, March 7, 2019 3:30PM - 3:42PM |
V17.00004: SCAN-L extended to an exchange-correlation free-energy density functional for extreme conditions Daniel Mejia-Rodriguez, Sam B Trickey The predictive potential of density functional theory (DFT) for simulation of systems under extreme conditions of temperature and pressure depends crucially on having an exchange-correlation (XC) free-energy functional that is accurate for such state conditions. Distinct from zero-temperature XC functionals, the XC free-energy functional must have an explicit temperature dependence. Recently, that has been achieved for the local density approximation [“KSDT”, Phys. Rev. Lett. 112, 076403 (2014) ] and generalized-gradient approximation [“KDT16”, Phys. Rev. Lett. 120, 076401 (2018) ]. |
Thursday, March 7, 2019 3:42PM - 3:54PM |
V17.00005: Fast First-Principles Predictions for Warm Dense Matter with Orbital-free Free Energy Density Functional Theory Kai Luo, Valentin Karasiev, Sam B Trickey Warm dense matter encompasses the phase-space region between ordinary condensed matter and |
Thursday, March 7, 2019 3:54PM - 4:06PM |
V17.00006: Approach to Orbital-Free DFT with Englert-Schwinger model Jouko Lehtomäki, Olga Lopez-Acevedo Orbital-free density functional theory (OFDFT) is a variant of DFT which tries to circumvent construction of Kohn-Sham orbitals in order to efficiently scale to larger system sizes. Most of the research on OFDFT is on improving the accuracy of the non-interacting kinetic energy T_s[n] approximation as a direct functional of density, which requires use of pseudopotentials. |
Thursday, March 7, 2019 4:06PM - 4:18PM |
V17.00007: WDM: Universal Hugoniot of Fluid Metals and Thomas-Fermi Theory William Nellis An equation of state at extreme conditions in Warm Dense Matter (WDM) is needed for exoplanets and Inertial Confinement Fusion. Development of theory for WDM is problematical because of the need for experimental data for verification. At shock pressures 0.5 - 20 TPa (200 Mbar) measured Hugoniot data of fluid metals [1] are essentially co-linear in US (UP), where US and UP are shock and particle velocity, respectively, essentially independent of material. Calculated shock temperatures of those data range from a few thousand K up to a million K. Those shock-compressed fluids are WDM with Minimum Metallic Conductivity (MMC) [2]. The linear fit to 40 measured data points is known as the Universal Hugoniot of Fluid Metals (UHFM), which is possible verification data for WDM theory. TFD is Thomas Fermi theory for ionized atoms, Fermi-Dirac statistics for electrons, and electron correlation [3]. A possible theory for why that co-linear fit is universal might be a common electron correlation function in TF theory that yields the UHFM for Al, Cu, Fe, Mo, Kr, Gd3Ga5O12, etc. |
Thursday, March 7, 2019 4:18PM - 4:30PM |
V17.00008: Isochoric heating of materials with intense ion pulses at the BELLA petawatt laser Thomas Schenkel, Sven Steinke, Qing Ji, Jianhui Bin, Stepan Bulanov, Jaehong Park, Wim Pieter Leemans We use the BELLA petawatt laser [1] to accelerate ions to multi-MeV energies at a repetition rate of up to 1 Hz [2]. Ion acceleration is now routinely conducted at BELLA in parallel to laser-plasma acceleration of electrons. For laser intensities in the 10^19 W/cm^2 regime, we find ion intensities up to 10^12 ions/shot with low divergence. When transported to a second target, ion pulses can drive the formation and annealing dynamics of defects and they can uniformly heat materials to temperatures of 1-10 eV, well into the warm dense matter regime [3]. Ion intensities can be tuned for materials processing at selected temperatures to form desired defect structures or to drive desired phase-transitions. We present results from ion acceleration and target heating campaigns, including color center synthesis for spin qubits in diamond. |
Thursday, March 7, 2019 4:30PM - 4:42PM |
V17.00009: XFEL diffraction measurements of shocked Fe and Fe alloys for planetary science Andrew Krygier, Marion Harmand, Bruno Albertazzi, Emma McBride, Karen Appel, Kohei Miyanishi, Norimasa Ozaki, Guillaume Fiquet Earth's core is composed of Fe mixed with small amounts of light elements like Si, O, and C. Determining the properties of high-pressure liquids, the melting curve, and solid phase relations of Fe and derivative alloys is important for understanding the cores of Earth and terrestrial exoplanets. High pressure and temperature conditions can be achieved with high power lasers, but the states are highly transient, and the inherently high strain rate introduces physics not expected to occur in planetary interiors. The recent advance of facilities with high-power lasers coupled to XFELs enables characterization of shocked states with the powerful suite of X-ray techniques used by the static community. Here we present results from recent ultrafast X-ray diffraction measurements of shocked Fe alloys at the coupled XFEL-optical laser facilities using the EH5 end station at the SACLA facility (Japan) and the LCLS end station MEC at SLAC National Accelerator Laboratory (USA). |
Thursday, March 7, 2019 4:42PM - 5:18PM |
V17.00010: Thermal conductivity and equation-of-state measurements in warm dense matter Invited Speaker: Yuan Ping Thermal conductivity is one of the most fundamental physical properties of matter. It determines the heat transport rate and has an enormous impact on a variety of mechanical, electrical, chemical, and nuclear systems. Thermal conduction is important in high energy density (HED) matter such as laboratory fusion plasmas, planetary cores, compact stars, and other celestial objects. Examples are in the ablation and instability growth in inertial confinement fusion (ICF) capsules, in energy loss from ICF hot spot, and in the evolution of Earth’s core-mantle boundary. Despite the importance of thermal conductivity in HED systems, experimental measurements under relevant conditions are scarce and challenging. We have developed a method of differential heating for thermal conductivity measurements. In this talk, experimental designs will be described for two different platforms: proton heating and x-ray laser heating. Data from various facilities on amorphous carbon, aluminum and iron will be presented and comparison with models will be discussed. |
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