Bulletin of the American Physical Society
19th Biennial Conference of the APS Topical Group on Shock Compression of Condensed Matter
Volume 60, Number 8
Sunday–Friday, June 14–19, 2015; Tampa, Florida
Session L5: First-Principles and MD III: Warm Dense Matter |
Hide Abstracts |
Chair: Aidan Thompson, Sandia National Laboratories, Stanimir Bonev, Lawrence Livermore National Laboratory/Dalhousie Room: Grand I/J |
Tuesday, June 16, 2015 3:45PM - 4:00PM |
L5.00001: Orbital-Free Molecular Dynamics Simulations at Extreme Conditions J.D. Kress, L.A. Collins, C. Ticknor Large-scale molecular dynamics (MD) simulations in an orbital-free (OF) density-functional theory (DFT) formulation have been performed for pure and mixed species over a broad range of temperatures (T) and densities ($\rho$) that includes the warm, dense matter and high-energy density physics regimes. A finite-temperature Thomas-Fermi-Dirac form with a local-density exchange-correlation potential and a regularized electron-ion interaction represents the quantum nature of the electrons. In particular, we examine the efficacy of the OFMD approach as an effective bridge between Kohn-Sham DFT MD at low temperatures and simple, fully-ionized plasma models at high temperatures. Comparisons against intermediate-range constructions such as the Yukawa and one-component plasmas are also made. We examine the mass transport (diffusion, viscosity) properties of various systems, ranging from light to heavy elements, including lithium hydride (LiH), mixtures of LiH with uranium, mixtures of deuterium-tritium (DT) with plutonium and mixtures of DT with plastic (CH). The OFMD mass transport results have been fitted to simple functions of $\rho$ and T suitable for use in hydrodynamics simulation codes. [Preview Abstract] |
Tuesday, June 16, 2015 4:00PM - 4:15PM |
L5.00002: ABSTRACT WITHDRAWN |
Tuesday, June 16, 2015 4:15PM - 4:30PM |
L5.00003: Shock compression of glow discharge polymer (GDP): density functional theory (DFT) simulations and experiments on Sandia's Z-machine K.R. Cochrane, T. Ao, S. Hamel, R.W. Lemke, M.E. Schoff, B.E. Blue, M.C. Herrmann, T.R. Mattsson Glow discharge polymer (GDP) is used extensively in inertial confinement fusion (ICF) capsules. Accurate knowledge of the equation of state (EOS) under shock and release is particularly important for high-fidelity design and analysis of ICF experiments since the capsule material is subject to several converging shocks as well as release towards the cryogenic fuel. We performed Density Functional Theory (DFT) based molecular dynamics simulations, to gain knowledge of the behavior of GDP - for example regarding the role of chemical dissociation during shock compression, we find that the dissociation regime along the Hugoniot extends from 50 GPa to 250 GPa. The shock pressures calculated from DFT are compared to experimental data taken on magnetically launched flyer plate impact experiments at Sandia's Z-machine. Large GDP samples were grown in a planar geometry to improve the sample quality and maintained in a nitrogen atmosphere following manufacturing, thus allowing for a direct comparison to the simulations. [Preview Abstract] |
Tuesday, June 16, 2015 4:30PM - 4:45PM |
L5.00004: Pressure in electronically excited warm dense metals Vladimir Stegailov, Petr Zhilyaev Non-equilibrium two-temperature warm dense metals consist of the ion subsystem that is subjected to structural transitions and involved in the mass transfer, and the electron subsystem that in various pulsed experiments absorbs energy and then evolves together with ions to equilibrium. Definition of pressure in such non-equilibrium systems causes certain controversy. In this work we make an attempt to clarify this definition that is vital for proper description of the whole relaxation process. Using the density functional theory we analyze on examples of Al and Au electronic pressure components in warm dense metals. Appealing to the Fermi gas model we elucidate a way to find a number of free delocalized electrons in warm dense metals. First results has been published in [1]. \\[4pt] [1] Stegailov V., Zhilyaev P. Pressure in electronically excited warm dense metals // Contrib. Plasma Phys. 2015. DOI:10.1002/ctpp.201400103 [Preview Abstract] |
Tuesday, June 16, 2015 4:45PM - 5:00PM |
L5.00005: Dynamic high pressure: why it makes metallic fluid hydrogen William Nellis Metallic fluid H (MFH) was made by dynamic compression decades after Wigner and Huntington (WH) predicted it in 1935. The density of MFH is within a few percent of the density predicted by WH. MFH was made by multiple-shock compression of liquid H2, which process is quasi-isentropic and thermally equilibrated. The compressions were isentropic but produced enough dissipation as temperature T and entropy S to drive the crossover from insulating H2 to metallic H at 9-fold compressed atomic H density. T and S were tuned by temporally shaping the applied pressure pulse such that H2 dissociated to H at sufficiently high density to make a highly degenerate metal. The basic ideas of dynamic compression, also known as supersonic, adiabatic, nonlinear hydrodynamics, were developed in the last half of the Nineteenth Century. Our purposes are to (i) present a brief review of dynamic compression and its affects on materials, (ii) review considerations that led to the sample holder designed specifically to make MFH, and (iii) present a inter-comparison of dynamic and static methods relative to their prospects for making metallic H. The full paper is published: J. Phys. Chem. Solids (2015), http://dx.doi.org/10.1016/j.jpcs.2014.12.007 [Preview Abstract] |
Follow Us |
Engage
Become an APS Member |
My APS
Renew Membership |
Information for |
About APSThe American Physical Society (APS) is a non-profit membership organization working to advance the knowledge of physics. |
© 2024 American Physical Society
| All rights reserved | Terms of Use
| Contact Us
Headquarters
1 Physics Ellipse, College Park, MD 20740-3844
(301) 209-3200
Editorial Office
100 Motor Pkwy, Suite 110, Hauppauge, NY 11788
(631) 591-4000
Office of Public Affairs
529 14th St NW, Suite 1050, Washington, D.C. 20045-2001
(202) 662-8700