Models of atoms in plasmas based on common formalism for bound and free electrons

Błeński, T.; Piron, R.; Caizergues, C.; Cichocki, B.

doi:10.1016/j.hedp.2013.06.003

Cited by 21 publications

(23 citation statements)

References 33 publications

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“…The NPA method applies for low T systems even with transient covalent bonding. Hence, we differ from Blenski et al [24] who hold that "... all quantum models seem to give unrealistic description of atoms in plasma at low T and high plasma densities". But in reality, the earliest successful applications of the NPA were for solids at T = 0.…”

Section: Introductioncontrasting

confidence: 96%

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Isochoric, isobaric, and ultrafast conductivities of aluminum, lithium, and carbon in the warm dense matter regime

et al. 2017

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We study the conductivities σ of (i) the equilibrium isochoric state (σis), (ii) the equilibrium isobaric state (σ ib ), and also the (iii) non-equilibrium ultrafast matter (UFM) state (σ uf ) with the ion temperature Ti less than the the electron temperature Te. Aluminum, lithium and carbon are considered, being increasingly complex warm dense matter (WDM) systems, with carbon having transient covalent bonds. First-principles calculations, i.e., neutral-pseudoatom (NPA) calculations and density-functional theory (DFT) with molecular-dynamics (MD) simulations, are compared where possible with experimental data to characterize σic, σ ib and σ uf . The NPA σ ib are closest to the available experimental data when compared to results from DFT+MD, where simulations of about 64-125 atoms are typically used. The published conductivities for Li are reviewed and the value at a temperature of 4.5 eV is examined using supporting X-ray Thomson scattering calculations. A physical picture of the variations of σ with temperature and density applicable to these materials is given. The insensitivity of σ to Te below 10 eV for carbon, compared to Al and Li, is clarified.

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Section: Introductioncontrasting

confidence: 96%

“…We typically use R c = 10r ws , i.e., a volume of some 1000 atoms. Several average-atom models [23,24] have similarities and significant differences among them and with the NPA method. These are reviewed in the Appendix and in Ref.…”

Section: Introductionmentioning

confidence: 99%

Isochoric, isobaric, and ultrafast conductivities of aluminum, lithium, and carbon in the warm dense matter regime

et al. 2017

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“…In atom‐in‐plasma models, the free electron density pileup δn f ( r ) is restricted to the ions sphere ; they cannot adequately capture such transient bonding effects, whereas the NPA used here does so as δn f ( r ) extends up to R c , covering the bonding region between the WS sphere of the central ion and any field ion. The NPA uses an “average ion,” which is rigorously a single DFT representative of all the different possible electronic configurations of the physical ion, including transient bonding states.…”

Section: The Neutral Pseudo‐atom Model (Npa) In the Context Of Complementioning

confidence: 59%

“…It should be emphasized that such features (i.e., the first peak in the g ( r ) etc.) are unlikely to be captured by the common ion‐sphere atom‐in‐plasma models or those based on Lieberman's model as they limit the electron pileup at the pseudo‐ions to within the ion‐spheres, where as the C–C bonding requires an increased density in middle regions between the ions outside the ions spheres.…”

Section: The Neutral Pseudo‐atom Model (Npa) In the Context Of Complementioning

confidence: 99%

Theory of complex fluids in the warm dense matter regime and application to an unusual phase transition in liquid carbon

Dharma‐wardana

2018

Contributions to Plasma Physics

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Data from recent laser‐shock experiments or from simulations using density functional theory (DFT), molecular dynamics (MD), path integrals etc. that are available for warm dense carbon are compared with the corresponding results predicted using the neutral pseudo‐atom [NPA] method. The NPA results are in good agreement not only with the 3–12 g/cm3 regimes that have been studied via path‐integral Monte Carlo methods but even at low densities and low temperatures where transient covalent bonding dominates ionic correlations. Thus, the “prepeak” due to the C–C bond at ∼1.4 Å and other features found in the pair distribution function g[r] from DFT + MD simulations at 0.86 eV and 3.7 g/cm3 and other densities etc. are recovered accurately in the NPA + HNC (hypernetted‐chain) calculations. The exploration of regimes not covered by previous studies is presented together with evidence of an unusual phase transition of carbon in the liquid state to a vapour, as seen from the loss of ion–ion correlations. An abrupt decrease in the number of free electrons per ion occurs simultaneously. A metallic liquid with strong ionic correlations arising from transient C–C bonds becomes a metallic vapour. This occurs when carbon at the density of ∼1.0 g/cm3 and mean ionization Z = 4 transits abruptly to a disordered mono‐atomic vapour at 7 eV, with Z ≃ 3. The behaviour of the pressure, compressibility and the electrical conductivity as well as physical quantities available from X‐ray Thomson scattering are presented across the tentatively proposed phase transition.

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“…Up to now the most used models are still essentially based on the ion-in-cell picture [12][13][14]. Some progress towards a variational formulation of quantum atom-in-plasma models was achieved [15][16][17][18][19][20][21][22]. However, it relies on a very simple hypothesis on ion-ion correlations.…”

Section: Introductionmentioning

confidence: 99%

Free-energy functional of the Debye–Hückel model of two-component plasmas

Błeński¹,

Piron²

2017

High Energy Density Physics

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We present a generalization of the Debye-Hückel free-energy-density functional of simple fluids to the case of two-component systems with arbitrary interaction potentials. It allows one to obtain the two-component Debye-Hückel integral equations through its minimization with respect to the pair correlation functions, leads to the correct form of the internal energy density, and fulfills the virial theorem. It is based on our previous idea, proposed for the one-component Debye-Hückel approach, and which was published recently [1]. We use the Debye-Kirkwood charging method in the same way as in [1], in order to build an expression of the free-energy density functional. Main properties of the two-component Debye-Hückel free energy are presented and discussed, including the virial theorem in the case of long-range interaction potentials.

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Models of atoms in plasmas based on common formalism for bound and free electrons

Cited by 21 publications

References 33 publications

Isochoric, isobaric, and ultrafast conductivities of aluminum, lithium, and carbon in the warm dense matter regime

Isochoric, isobaric, and ultrafast conductivities of aluminum, lithium, and carbon in the warm dense matter regime

Theory of complex fluids in the warm dense matter regime and application to an unusual phase transition in liquid carbon

Free-energy functional of the Debye–Hückel model of two-component plasmas

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