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Svensson P, Campbell T, Graziani F, Moldabekov Z, Lyu N, Batista VS, Richardson S, Vinko SM, Gregori G. Development of a new quantum trajectory molecular dynamics framework. PHILOSOPHICAL TRANSACTIONS. SERIES A, MATHEMATICAL, PHYSICAL, AND ENGINEERING SCIENCES 2023; 381:20220325. [PMID: 37393934 PMCID: PMC10315217 DOI: 10.1098/rsta.2022.0325] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/14/2022] [Accepted: 01/19/2023] [Indexed: 07/04/2023]
Abstract
An extension to the wave packet description of quantum plasmas is presented, where the wave packet can be elongated in arbitrary directions. A generalized Ewald summation is constructed for the wave packet models accounting for long-range Coulomb interactions and fermionic effects are approximated by purpose-built Pauli potentials, self-consistent with the wave packets used. We demonstrate its numerical implementation with good parallel support and close to linear scaling in particle number, used for comparisons with the more common wave packet employing isotropic states. Ground state and thermal properties are compared between the models with differences occurring primarily in the electronic subsystem. Especially, the electrical conductivity of dense hydrogen is investigated where a 15% increase in DC conductivity can be seen in our wave packet model compared with other models. This article is part of the theme issue 'Dynamic and transient processes in warm dense matter'.
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Affiliation(s)
- Pontus Svensson
- Department of Physics, University of Oxford, Parks Road, Oxford OX1 3PU, UK
| | - Thomas Campbell
- Department of Physics, University of Oxford, Parks Road, Oxford OX1 3PU, UK
| | - Frank Graziani
- Lawrence Livermore National Laboratory, Livermore, CA 94550, USA
| | - Zhandos Moldabekov
- Center of Advanced Systems Understanding (CASUS), D-02826 Görlitz, Germany
- Helmholtz-Zentrum Dresden-Rossendorf (HZDR), D-01328 Dresden, Germany
| | - Ningyi Lyu
- Department of Chemistry, Yale University, New Haven, CT 06520, USA
| | - Victor S Batista
- Department of Chemistry, Yale University, New Haven, CT 06520, USA
- Yale Quantum Institute, Yale University, New Haven, CT 06511, USA
| | | | - Sam M Vinko
- Department of Physics, University of Oxford, Parks Road, Oxford OX1 3PU, UK
- Central Laser Facility, STFC Rutherford Appleton Laboratory, Didcot OX11 0QX, UK
| | - Gianluca Gregori
- Department of Physics, University of Oxford, Parks Road, Oxford OX1 3PU, UK
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2
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Schörner M, Bethkenhagen M, Döppner T, Kraus D, Fletcher LB, Glenzer SH, Redmer R. X-ray Thomson scattering spectra from density functional theory molecular dynamics simulations based on a modified Chihara formula. Phys Rev E 2023; 107:065207. [PMID: 37464593 DOI: 10.1103/physreve.107.065207] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2023] [Accepted: 05/10/2023] [Indexed: 07/20/2023]
Abstract
We study ab initio approaches for calculating x-ray Thomson scattering spectra from density functional theory molecular dynamics simulations based on a modified Chihara formula that expresses the inelastic contribution in terms of the dielectric function. We study the electronic dynamic structure factor computed from the Mermin dielectric function using an ab initio electron-ion collision frequency in comparison to computations using a linear-response time-dependent density functional theory (LR-TDDFT) framework for hydrogen and beryllium and investigate the dispersion of free-free and bound-free contributions to the scattering signal. A separate treatment of these contributions, where only the free-free part follows the Mermin dispersion, shows good agreement with LR-TDDFT results for ambient-density beryllium, but breaks down for highly compressed matter where the bound states become pressure ionized. LR-TDDFT is used to reanalyze x-ray Thomson scattering experiments on beryllium demonstrating strong deviations from the plasma conditions inferred with traditional analytic models at small scattering angles.
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Affiliation(s)
| | - Mandy Bethkenhagen
- École Normale Supérieure de Lyon, Laboratoire de Géologie de Lyon, CNRS UMR 5276, 69364 Lyon, Cedex 07, France
- Institute of Science and Technology Austria, Am Campus 1, 3400 Klosterneuburg, Austria
| | - Tilo Döppner
- Lawrence Livermore National Laboratory, Livermore, California 94551, USA
| | - Dominik Kraus
- University of Rostock, Institute of Physics, 18051 Rostock, Germany
- Helmholtz-Zentrum Dresden-Rossendorf, 01328 Dresden, Germany
| | - Luke B Fletcher
- SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA
| | | | - Ronald Redmer
- University of Rostock, Institute of Physics, 18051 Rostock, Germany
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3
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Döppner T, Bethkenhagen M, Kraus D, Neumayer P, Chapman DA, Bachmann B, Baggott RA, Böhme MP, Divol L, Falcone RW, Fletcher LB, Landen OL, MacDonald MJ, Saunders AM, Schörner M, Sterne PA, Vorberger J, Witte BBL, Yi A, Redmer R, Glenzer SH, Gericke DO. Observing the onset of pressure-driven K-shell delocalization. Nature 2023:10.1038/s41586-023-05996-8. [PMID: 37225995 DOI: 10.1038/s41586-023-05996-8] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2022] [Accepted: 03/22/2023] [Indexed: 05/26/2023]
Abstract
The gravitational pressure in many astrophysical objects exceeds one gigabar (one billion atmospheres)1-3, creating extreme conditions where the distance between nuclei approaches the size of the K shell. This close proximity modifies these tightly bound states and, above a certain pressure, drives them into a delocalized state4. Both processes substantially affect the equation of state and radiation transport and, therefore, the structure and evolution of these objects. Still, our understanding of this transition is far from satisfactory and experimental data are sparse. Here we report on experiments that create and diagnose matter at pressures exceeding three gigabars at the National Ignition Facility5 where 184 laser beams imploded a beryllium shell. Bright X-ray flashes enable precision radiography and X-ray Thomson scattering that reveal both the macroscopic conditions and the microscopic states. The data show clear signs of quantum-degenerate electrons in states reaching 30 times compression, and a temperature of around two million kelvins. At the most extreme conditions, we observe strongly reduced elastic scattering, which mainly originates from K-shell electrons. We attribute this reduction to the onset of delocalization of the remaining K-shell electron. With this interpretation, the ion charge inferred from the scattering data agrees well with ab initio simulations, but it is significantly higher than widely used analytical models predict6.
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Affiliation(s)
- T Döppner
- Lawrence Livermore National Laboratory, Livermore, CA, USA.
| | - M Bethkenhagen
- Institute of Physics, University of Rostock, Rostock, Germany
- École Normale Supérieure de Lyon, LGLTPE, CNRS UMR 5276, Lyon, France
| | - D Kraus
- Institute of Physics, University of Rostock, Rostock, Germany
- Department of Physics, University of California Berkeley, Berkeley, CA, USA
- Helmholtz-Zentrum Dresden-Rossendorf, Dresden, Germany
| | - P Neumayer
- GSI Helmholtz-Zentrum für Schwerionenforschung, Darmstadt, Germany
| | | | - B Bachmann
- Lawrence Livermore National Laboratory, Livermore, CA, USA
| | - R A Baggott
- The John Adams Institute for Accelerator Science, Imperial College London, London, UK
| | - M P Böhme
- Helmholtz-Zentrum Dresden-Rossendorf, Dresden, Germany
- Center for Advanced Systems Understanding (CASUS), Görlitz, Germany
- Technische Universität Dresden, Dresden, Germany
| | - L Divol
- Lawrence Livermore National Laboratory, Livermore, CA, USA
| | - R W Falcone
- Department of Physics, University of California Berkeley, Berkeley, CA, USA
| | - L B Fletcher
- SLAC National Accelerator Laboratory, Menlo Park, CA, USA
| | - O L Landen
- Lawrence Livermore National Laboratory, Livermore, CA, USA
| | - M J MacDonald
- Lawrence Livermore National Laboratory, Livermore, CA, USA
| | - A M Saunders
- Lawrence Livermore National Laboratory, Livermore, CA, USA
| | - M Schörner
- Institute of Physics, University of Rostock, Rostock, Germany
| | - P A Sterne
- Lawrence Livermore National Laboratory, Livermore, CA, USA
| | - J Vorberger
- Helmholtz-Zentrum Dresden-Rossendorf, Dresden, Germany
| | - B B L Witte
- Institute of Physics, University of Rostock, Rostock, Germany
- SLAC National Accelerator Laboratory, Menlo Park, CA, USA
| | - A Yi
- Los Alamos National Laboratory, Los Alamos, NM, USA
| | - R Redmer
- Institute of Physics, University of Rostock, Rostock, Germany
| | - S H Glenzer
- SLAC National Accelerator Laboratory, Menlo Park, CA, USA
| | - D O Gericke
- Centre for Fusion, Space and Astrophysics, Department of Physics, University of Warwick, Coventry, UK
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Dharma-Wardana MWC. Ionization of carbon at 10-100 times the diamond density and in the 10^{6} K temperature range. Phys Rev E 2021; 104:015201. [PMID: 34412196 DOI: 10.1103/physreve.104.015201] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2021] [Accepted: 06/08/2021] [Indexed: 11/07/2022]
Abstract
The behavior of partially ionized hot compressed matter is critical to the study of planetary interiors as well as nuclear fusion studies. A recent quantum study of carbon in the 10-70 Gbar range and at a temperature of 100 eV used N-atom density functional theory (DFT) with N∼32-64 and molecular dynamics (MD). This involves band-structure-type electronic calculations and averaging over many MD-generated ion configurations. The calculated average number of free electrons per ion, viz., Z[over ¯], was systematically higher than from a standard average-atom quantum calculation. To clarify this offset, we examine the effect of the self-interaction error in such estimates and the possibility of carbon being in a granular plasma state containing Coulomb crystals with a magic number. The electrical conductivity, pressure, and compressibility of the carbon system are examined. The very low conductivity and the high-Z[over ¯] results of DFT MD point to the existence of carbon in a complex, nonuniform, low-conducting dispersed phase, possibly containing magic-number Coulomb crystals. The neutral pseudoatom estimate of Z[over ¯], conductivity, compressibility, and pressure reported here pertain to the uniform liquid.
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Beuermann TN, Redmer R, Bornath T. Thomson scattering from dense inhomogeneous plasmas. Phys Rev E 2019; 99:053205. [PMID: 31212444 DOI: 10.1103/physreve.99.053205] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2018] [Indexed: 11/07/2022]
Abstract
X-ray Thomson scattering experiments in the soft and hard x-ray regime yield information on fundamental parameters of high-density systems. Pump-probe experiments with variable time delay provide insight into the excitation and relaxation dynamics in dense plasmas. On short time scales, a local thermodynamic equilibrium description might not be sufficient. Besides nonequilibrium effects on the electron distribution function, spatial inhomogeneities influence the scattering signal. Generalizing previous approaches of Belyi [Phys. Rev. E 97, 053204 (2018)2470-004510.1103/PhysRevE.97.053204] and Kozlowski et al. [Sci. Rep. 6, 24283 (2016)2045-232210.1038/srep24283], we discuss implications for Thomson scattering spectra for inhomogeneous plasmas in the warm dense matter regime based on a gradient expansion within real-time Green's-functions theory. Especially in the collective scattering regime, Thomson scattering spectra are modifed substantially by spatial inhomogeneities. Within a first-order gradient expansion, the dispersion relation for plasmons is determined. In particular, the ratio of the heights of the plasmon peaks is changed which prevents a simple estimation of the plasma temperature from the detailed balance relation.
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Affiliation(s)
- T-N Beuermann
- Institut für Physik, Universität Rostock, D-18051 Rostock, Germany
| | - R Redmer
- Institut für Physik, Universität Rostock, D-18051 Rostock, Germany
| | - Th Bornath
- Institut für Physik, Universität Rostock, D-18051 Rostock, Germany
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6
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Moldabekov ZA, Kählert H, Dornheim T, Groth S, Bonitz M, Ramazanov TS. Dynamical structure factor of strongly coupled ions in a dense quantum plasma. Phys Rev E 2019; 99:053203. [PMID: 31212426 DOI: 10.1103/physreve.99.053203] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2019] [Indexed: 06/09/2023]
Abstract
The dynamical structure factor (DSF) of strongly coupled ions in dense plasmas with partially and strongly degenerate electrons is investigated. The main focus is on the impact of electronic correlations (nonideality) on the ionic DSF. The latter is computed by carrying out molecular dynamics (MD) simulations with a screened ion-ion interaction potential. The electronic screening is taken into account by invoking the Singwi-Tosi-Land-Sjölander approximation, and it is compared to the MD simulation data obtained considering the electronic screening in the random phase approximation and using the Yukawa potential. We find that electronic correlations lead to lower values of the ion-acoustic mode frequencies and to an extension of the applicability limit with respect to the wave-number of a hydrodynamic description. Moreover, we show that even in the limit of weak electronic coupling, electronic correlations have a nonnegligible impact on the ionic longitudinal sound speed. Additionally, the applicability of the Yukawa potential with an adjustable screening parameter is discussed, which will be of interest, e.g., for the interpretation of experimental results for the ionic DSF of dense plasmas.
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Affiliation(s)
- Zh A Moldabekov
- Institut für Theoretische Physik und Astrophysik, Christian-Albrechts-Universität zu Kiel, Leibnizstraße 15, 24098 Kiel, Germany
- Institute for Experimental and Theoretical Physics, Al-Farabi Kazakh National University, 71 Al-Farabi Street, 050040 Almaty, Kazakhstan
| | - H Kählert
- Institut für Theoretische Physik und Astrophysik, Christian-Albrechts-Universität zu Kiel, Leibnizstraße 15, 24098 Kiel, Germany
| | - T Dornheim
- Institut für Theoretische Physik und Astrophysik, Christian-Albrechts-Universität zu Kiel, Leibnizstraße 15, 24098 Kiel, Germany
| | - S Groth
- Institut für Theoretische Physik und Astrophysik, Christian-Albrechts-Universität zu Kiel, Leibnizstraße 15, 24098 Kiel, Germany
| | - M Bonitz
- Institut für Theoretische Physik und Astrophysik, Christian-Albrechts-Universität zu Kiel, Leibnizstraße 15, 24098 Kiel, Germany
| | - T S Ramazanov
- Institute for Experimental and Theoretical Physics, Al-Farabi Kazakh National University, 71 Al-Farabi Street, 050040 Almaty, Kazakhstan
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7
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Moldabekov ZA, Groth S, Dornheim T, Kählert H, Bonitz M, Ramazanov TS. Structural characteristics of strongly coupled ions in a dense quantum plasma. Phys Rev E 2018; 98:023207. [PMID: 30253556 DOI: 10.1103/physreve.98.023207] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2018] [Indexed: 06/08/2023]
Abstract
The structural properties of strongly coupled ions in dense plasmas with moderately to strongly degenerate electrons are investigated in the framework of the one-component plasma model of ions interacting through a screened pair interaction potential. Special focus is put on the description of the electronic screening in the Singwi-Tosi-Land-Sjölander (STLS) approximation. Different cross-checks and analyses using ion potentials obtained from ground-state quantum Monte Carlo data, the random phase approximation (RPA), and existing analytical models are presented for the computation of the structural properties, such as the pair distribution and the static structure factor, of strongly coupled ions. The results are highly sensitive to the features of the screened pair interaction potential. This effect is particularly visible in the static structure factor. The applicability range of the screened potential computed from STLS is identified in terms of density and temperature of the electrons. It is demonstrated that at r_{s}>1, where r_{s} is the ratio of the mean interelectronic distance to the Bohr radius, electronic correlations beyond RPA have a nonnegligible effect on the structural properties. Additionally, the applicability of the hypernetted chain approximation for the calculation of the structural properties using the screened pair interaction potential is analyzed employing the effective coupling parameter approach.
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Affiliation(s)
- Zh A Moldabekov
- Institut für Theoretische Physik und Astrophysik, Christian-Albrechts-Universität zu Kiel, Leibnizstraße 15, 24098 Kiel, Germany
- Institute for Experimental and Theoretical Physics, Al-Farabi Kazakh National University, 71 Al-Farabi str., 050040 Almaty, Kazakhstan
| | - S Groth
- Institut für Theoretische Physik und Astrophysik, Christian-Albrechts-Universität zu Kiel, Leibnizstraße 15, 24098 Kiel, Germany
| | - T Dornheim
- Institut für Theoretische Physik und Astrophysik, Christian-Albrechts-Universität zu Kiel, Leibnizstraße 15, 24098 Kiel, Germany
| | - H Kählert
- Institut für Theoretische Physik und Astrophysik, Christian-Albrechts-Universität zu Kiel, Leibnizstraße 15, 24098 Kiel, Germany
| | - M Bonitz
- Institut für Theoretische Physik und Astrophysik, Christian-Albrechts-Universität zu Kiel, Leibnizstraße 15, 24098 Kiel, Germany
| | - T S Ramazanov
- Institute for Experimental and Theoretical Physics, Al-Farabi Kazakh National University, 71 Al-Farabi str., 050040 Almaty, Kazakhstan
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8
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Driver KP, Soubiran F, Militzer B. Path integral Monte Carlo simulations of warm dense aluminum. Phys Rev E 2018; 97:063207. [PMID: 30011453 DOI: 10.1103/physreve.97.063207] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2017] [Indexed: 06/08/2023]
Abstract
We perform first-principles path integral Monte Carlo (PIMC) and density functional theory molecular dynamics (DFT-MD) calculations to explore warm dense matter states of aluminum. Our equation of state (EOS) simulations cover a wide density-temperature range of 0.1-32.4gcm^{-3} and 10^{4}-10^{8} K. Since PIMC and DFT-MD accurately treat effects of the atomic shell structure, we find two compression maxima along the principal Hugoniot curve attributed to K-shell and L-shell ionization. The results provide a benchmark for widely used EOS tables, such as SESAME, QEOS, and models based on Thomas-Fermi and average-atom techniques. A subsequent multishock analysis provides a quantitative assessment for how much heating occurs relative to an isentrope in multishock experiments. Finally, we compute heat capacity, pair-correlation functions, the electronic density of states, and 〈Z〉 to reveal the evolution of the plasma structure and ionization behavior.
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Affiliation(s)
- K P Driver
- Department of Earth and Planetary Science, University of California, Berkeley, California 94720, USA
| | - F Soubiran
- Department of Earth and Planetary Science, University of California, Berkeley, California 94720, USA
| | - B Militzer
- Department of Earth and Planetary Science, University of California, Berkeley, California 94720, USA
- Department of Astronomy, University of California, Berkeley, California 94720, USA
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9
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Vorberger J, Chapman DA. Quantum theory for the dynamic structure factor in correlated two-component systems in nonequilibrium: Application to x-ray scattering. Phys Rev E 2018; 97:013203. [PMID: 29448372 DOI: 10.1103/physreve.97.013203] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2017] [Indexed: 06/08/2023]
Abstract
We present a quantum theory for the dynamic structure factors in nonequilibrium, correlated, two-component systems such as plasmas or warm dense matter. The polarization function, which is needed as the input for the calculation of the structure factors, is calculated in nonequilibrium based on a perturbation expansion in the interaction strength. To make our theory applicable for x-ray scattering, a generalized Chihara decomposition for the total electron structure factor in nonequilibrium is derived. Examples are given and the influence of correlations and exchange on the structure and the x-ray-scattering spectrum are discussed for a model nonequilibrium distribution, as often encountered during laser heating of materials, as well as for two-temperature systems.
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Affiliation(s)
- J Vorberger
- Institute of Radiation Physics, Helmholtz-Zentrum Dresden-Rossendorf e.V., 01328 Dresden, Germany
| | - D A Chapman
- AWE plc, Aldermaston, Reading RG7 4PR, United Kingdom
- Centre for Fusion, Space and Astrophysics, University of Warwick, Coventry CV4 7AL, United Kingdom
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10
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Clérouin J, Desbiens N, Dubois V, Arnault P. Bayesian inference of x-ray diffraction spectra from warm dense matter with the one-component-plasma model. Phys Rev E 2017; 94:061202. [PMID: 28085351 DOI: 10.1103/physreve.94.061202] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2016] [Indexed: 11/07/2022]
Abstract
We show that the Bayesian inference of recently measured x-ray diffraction spectra from laser-shocked aluminum [L. B. Fletcher et al., Nat. Photon. 9, 274 (2015)10.1038/nphoton.2015.41] with the one-component-plasma (OCP) model performs remarkably well at estimating the ionic density and temperature. This statistical approach requires many evaluations of the OCP static structure factor, which were done using a recently derived analytic fit. The atomic form factor is approximated by an exponential function in the diffraction window of the first peak. The electronic temperature is then estimated from a comparison of this approximated form factor with the electronic structure of an average atom model. Out-of-equilibrium states, with electrons hotter than ions, are diagnosed for the spectra obtained early after the pump, whereas at a late time delay the plasma is at thermal equilibrium. Apart from the present findings, this OCP-based modeling of warm dense matter has an important role to play in the interpretation of x-ray Thomson scattering measurements currently performed at large laser facilities.
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Harbour L, Dharma-Wardana MWC, Klug DD, Lewis LJ. Pair potentials for warm dense matter and their application to x-ray Thomson scattering in aluminum and beryllium. Phys Rev E 2016; 94:053211. [PMID: 27967139 DOI: 10.1103/physreve.94.053211] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2016] [Indexed: 06/06/2023]
Abstract
Ultrafast laser experiments yield increasingly reliable data on warm dense matter, but their interpretation requires theoretical models. We employ an efficient density functional neutral-pseudoatom hypernetted-chain (NPA-HNC) model with accuracy comparable to ab initio simulations and which provides first-principles pseudopotentials and pair potentials for warm-dense matter. It avoids the use of (i) ad hoc core-repulsion models and (ii) "Yukawa screening" and (iii) need not assume ion-electron thermal equilibrium. Computations of the x-ray Thomson scattering (XRTS) spectra of aluminum and beryllium are compared with recent experiments and with density-functional-theory molecular-dynamics (DFT-MD) simulations. The NPA-HNC structure factors, compressibilities, phonons, and conductivities agree closely with DFT-MD results, while Yukawa screening gives misleading results. The analysis of the XRTS data for two of the experiments, using two-temperature quasi-equilibrium models, is supported by calculations of their temperature relaxation times.
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Affiliation(s)
- L Harbour
- Département de Physique and Regroupement Québécois sur les Matériaux de Pointe, Université de Montréal, C.P. 6128, Succursale Centre-Ville, Montréal, Québec, Canada H3C 3J7
| | | | - D D Klug
- National Research Council of Canada, Ottawa, Ontario, Canada K1A 0R6
| | - L J Lewis
- Département de Physique and Regroupement Québécois sur les Matériaux de Pointe, Université de Montréal, C.P. 6128, Succursale Centre-Ville, Montréal, Québec, Canada H3C 3J7
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12
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Current Issues in Finite-T Density-Functional Theory and Warm-Correlated Matter †. COMPUTATION 2016. [DOI: 10.3390/computation4020016] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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13
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Clérouin J, Arnault P, Ticknor C, Kress JD, Collins LA. Unified Concept of Effective One Component Plasma for Hot Dense Plasmas. PHYSICAL REVIEW LETTERS 2016; 116:115003. [PMID: 27035306 DOI: 10.1103/physrevlett.116.115003] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/06/2015] [Indexed: 06/05/2023]
Abstract
Orbital-free molecular dynamics simulations are used to benchmark two popular models for hot dense plasmas: the one component plasma (OCP) and the Yukawa model. A unified concept emerges where an effective OCP (EOCP) is constructed from the short-range structure of the plasma. An unambiguous ionization and the screening length can be defined and used for a Yukawa system, which reproduces the long-range structure with finite compressibility. Similarly, the dispersion relation of longitudinal waves is consistent with the screened model at vanishing wave number but merges with the OCP at high wave number. Additionally, the EOCP reproduces the overall relaxation time scales of the correlation functions associated with ionic motion. In the hot dense regime, this unified concept of EOCP can be fruitfully applied to deduce properties such as the equation of state, ionic transport coefficients, and the ion feature in x-ray Thomson scattering experiments.
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Affiliation(s)
| | | | - Christopher Ticknor
- Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| | - Joel D Kress
- Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| | - Lee A Collins
- Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
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14
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Baczewski AD, Shulenburger L, Desjarlais MP, Hansen SB, Magyar RJ. X-ray Thomson Scattering in Warm Dense Matter without the Chihara Decomposition. PHYSICAL REVIEW LETTERS 2016; 116:115004. [PMID: 27035307 DOI: 10.1103/physrevlett.116.115004] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/17/2015] [Indexed: 06/05/2023]
Abstract
X-ray Thomson scattering is an important experimental technique used to measure the temperature, ionization state, structure, and density of warm dense matter (WDM). The fundamental property probed in these experiments is the electronic dynamic structure factor. In most models, this is decomposed into three terms [J. Chihara, J. Phys. F 17, 295 (1987)] representing the response of tightly bound, loosely bound, and free electrons. Accompanying this decomposition is the classification of electrons as either bound or free, which is useful for gapped and cold systems but becomes increasingly questionable as temperatures and pressures increase into the WDM regime. In this work we provide unambiguous first principles calculations of the dynamic structure factor of warm dense beryllium, independent of the Chihara form, by treating bound and free states under a single formalism. The computational approach is real-time finite-temperature time-dependent density functional theory (TDDFT) being applied here for the first time to WDM. We compare results from TDDFT to Chihara-based calculations for experimentally relevant conditions in shock-compressed beryllium.
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Affiliation(s)
- A D Baczewski
- Center for Computing Research, Sandia National Laboratories, Albuquerque, New Mexico 87185, USA
| | - L Shulenburger
- Pulsed Power Sciences Center, Sandia National Laboratories, Albuquerque, New Mexico 87185, USA
| | - M P Desjarlais
- Pulsed Power Sciences Center, Sandia National Laboratories, Albuquerque, New Mexico 87185, USA
| | - S B Hansen
- Pulsed Power Sciences Center, Sandia National Laboratories, Albuquerque, New Mexico 87185, USA
| | - R J Magyar
- Center for Computing Research, Sandia National Laboratories, Albuquerque, New Mexico 87185, USA
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