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 BruyeresleChatel Room: BCEC 156A 
Thursday, March 7, 2019 2:30PM  3:06PM 
V17.00001: Modeling Materials at Extreme Conditions for High EnergyDensity Science Invited Speaker: Stephanie Hansen Modern High EnergyDensity 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 equationofstate, 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 selfconsistent atomicscale model of material at extreme conditions. Generating equations of state, transport properties (thermal and electrical conductivities, opacities, stopping powers) and diagnostic signatures (Xray 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 wellunderstood. A root cause is our limited understanding of matter under extreme conditions (MEC)  pressures in the GPaTPa range and temperatures (T) up to 10^{5 } 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 KohnSham density functional theory (KSDFT) 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}). 

V17.00003: ABSTRACT WITHDRAWN

Thursday, March 7, 2019 3:30PM  3:42PM 
V17.00004: SCANL extended to an exchangecorrelation freeenergy density functional for extreme conditions Daniel MejiaRodriguez, 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 exchangecorrelation (XC) freeenergy functional that is accurate for such state conditions. Distinct from zerotemperature XC functionals, the XC freeenergy 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 generalizedgradient approximation [“KDT16”, Phys. Rev. Lett. 120, 076401 (2018) ]. 
Thursday, March 7, 2019 3:42PM  3:54PM 
V17.00005: Fast FirstPrinciples Predictions for Warm Dense Matter with Orbitalfree Free Energy Density Functional Theory Kai Luo, Valentin Karasiev, Sam B Trickey Warm dense matter encompasses the phasespace region between ordinary condensed matter and 
Thursday, March 7, 2019 3:54PM  4:06PM 
V17.00006: Approach to OrbitalFree DFT with EnglertSchwinger model Jouko Lehtomäki, Olga LopezAcevedo Orbitalfree density functional theory (OFDFT) is a variant of DFT which tries to circumvent construction of KohnSham orbitals in order to efficiently scale to larger system sizes. Most of the research on OFDFT is on improving the accuracy of the noninteracting 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 ThomasFermi 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 colinear in U_{S }(U_{P}), where U_{S }and U_{P} 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 shockcompressed 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, FermiDirac statistics for electrons, and electron correlation [3]. A possible theory for why that colinear fit is universal might be a common electron correlation function in TF theory that yields the UHFM for Al, Cu, Fe, Mo, Kr, Gd_{3}Ga_{5}O_{12}, 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 multiMeV energies at a repetition rate of up to 1 Hz [2]. Ion acceleration is now routinely conducted at BELLA in parallel to laserplasma 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 110 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 phasetransitions. 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 highpressure 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 highpower lasers coupled to XFELs enables characterization of shocked states with the powerful suite of Xray techniques used by the static community. Here we present results from recent ultrafast Xray diffraction measurements of shocked Fe alloys at the coupled XFELoptical 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 equationofstate 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 coremantle 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 xray 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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