<i>Ab initio</i>approach to model x-ray diffraction in warm dense matter

Vorberger, Jan; Gericke, Dirk O.

doi:10.1103/physreve.91.033112

Cited by 17 publications

(19 citation statements)

References 45 publications

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“…For u-Be at a temperature of 12 eV, similar results for the ion feature were obtained in Ref. [20]. We conclude that our ab initio method for calculating the ion feature enables an accurate determination of the plasma parameters density and temperature because no approximation (except the choice of the XC functional used in the DFT calculations) has been made, neither for the form factors, nor for the ion-ion structure factor.…”

Section: Ion Featuresupporting

confidence: 75%

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Ab initiocalculation of the ion feature in x-ray Thomson scattering

et al. 2015

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The spectrum of x-ray Thomson scattering is proportional to the dynamic structure factor. An important contribution is the ion feature which describes elastic scattering of x rays off electrons. We apply an ab initio method for the calculation of the form factor of bound electrons, the slope of the screening cloud of free electrons, and the ion-ion structure factor in warm dense beryllium. With the presented method we can calculate the ion feature from first principles. These results will facilitate a better understanding of x-ray scattering in warm dense matter and an accurate measurement of ion temperatures which would allow determining nonequilibrium conditions, e.g., along shock propagation.

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Section: Ion Featuresupporting

confidence: 75%

“…Density-functional-theory molecular-dynamics (DFT-MD) simulations for the ion feature of u-Be and CH were performed recently [20]. Applying the VASP package [21][22][23], ionic configurations were obtained.…”

Section: Introductionmentioning

confidence: 99%

Ab initiocalculation of the ion feature in x-ray Thomson scattering

et al. 2015

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“…In Ref. [19] n(q) is calculated from an externally obtained pseudopotential (for Al). Since such potentials are not available for WDM conditions, the authors use an Ashcroft empty-core potential U emp (q) [20,21].…”

Section: Introductionmentioning

confidence: 99%

Pair potentials for warm dense matter and their application to x-ray Thomson scattering in aluminum and beryllium

et al. 2016

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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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“…The decomposition of the equilibrium electron DSF according to Chihara [49,96] is the basis for the analysis of experimental x-ray scattering spectra and a cornerstone of interaction between theory and experiment (see, e.g., [53,56] amongst other works). The Chihara formula uses the chemical picture to distinguish between free and bound electron contributions in a semi-classical framework.…”

Section: Decomposition Of the Dynamic Structure Factor In Non-equimentioning

confidence: 99%

Quantum theory for the dynamic structure factor in correlated two-component systems in nonequilibrium: Application to x-ray scattering

Vorberger

Chapman

2018

Phys. Rev. E

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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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Ab initioapproach to model x-ray diffraction in warm dense matter

Cited by 17 publications

References 45 publications

Ab initiocalculation of the ion feature in x-ray Thomson scattering

Ab initiocalculation of the ion feature in x-ray Thomson scattering

Pair potentials for warm dense matter and their application to x-ray Thomson scattering in aluminum and beryllium

Quantum theory for the dynamic structure factor in correlated two-component systems in nonequilibrium: Application to x-ray scattering

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