Thermal excitation signals in the inhomogeneous warm dense electron gas

Moldabekov, Zhandos A.; Dornheim, Tobias; Cangi, Attila

doi:10.1038/s41598-022-05034-z

Cited by 16 publications

(7 citation statements)

References 87 publications

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“…Specifically, the interpretation of current XRTS experiments is solely based on LRT, [ 45 ] and the inference of important plasma parameters such as the electronic temperature T e is notoriously difficult. [ 44 ] In this context, Moldabekov et al [ 82 ] have recently suggested that the application of an external perturbation to generate inhomogeneous WDM samples on purpose leads to a modified experimental signal, that more strongly depends on T e . Naturally, the accurate theoretical description in this case will have to consider the mode‐coupling between this external potential and the XRTS probe, and the current LFC‐based theory is uniquely suited for this endeavour.…”

Section: Summary and Discussionmentioning

confidence: 99%

Nonlinear interaction of external perturbations in warm dense matter

Dornheim

Vorberger

Moldabekov

et al. 2022

Contributions to Plasma Physics

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We present extensive new ab initio path integral Monte Carlo (PIMC) results for an electron gas at warm dense matter conditions that is subject to multiple harmonic perturbations. In addition to the previously investigated nonlinear effects at the original wave number (Dornheim et al., Phys. Rev. Lett., 2020, 125, 085001) and the excitation of higher harmonics (Dornheim et al., Phys. Rev. Res., 2021, 3, 033231), the presence of multiple external potentials leads to mode-coupling effects, which constitute the dominant nonlinear effect and lead to a substantially more complicated density response compared to linear response theory. One possibility to estimate mode-coupling effects from a PIMC simulation of the unperturbed system is given in terms of generalized imaginary-time correlation functions that have been recently introduced by Dornheim et al. (J. Chem. Phys., 2021, 155, 054110). In addition, we extend our previous analytical theory of the nonlinear density response of the electron gas in terms of the static local field correction (Dornheim et al., 2020, Phys. Rev. Lett., 125, 235001), which allows for a highly accurate description of the PIMC results with negligible computational cost.

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Section: Summary and Discussionmentioning

confidence: 99%

Nonlinear interaction of external perturbations in warm dense matter

Dornheim

Vorberger

Moldabekov

et al. 2022

Contributions to Plasma Physics

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“…The results at θ = 0.01 are presented for N = 38 electrons, and those at θ = 1.0 for N = 14 electrons. We note that finite-size effects have been extensively investigated in the literature − and are expected to be small for these conditions. The corresponding cell lengths ( L ) are 10.839 and 7.7703 Bohr, respectively.…”

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confidence: 93%

Non-empirical Mixing Coefficient for Hybrid XC Functionals from Analysis of the XC Kernel

Moldabekov

Lokamani

Vorberger

et al. 2023

J. Phys. Chem. Lett.

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We present an analysis of the static exchange-correlation (XC) kernel computed from hybrid functionals with a single mixing coefficient such as PBE0 and PBE0–1/3. We break down the hybrid XC kernels into the exchange and correlation parts using the Hartree–Fock functional, the exchange-only PBE, and the correlation-only PBE. This decomposition is combined with exact data for the static XC kernel of the uniform electron gas and an Airy gas model within a subsystem functional approach. This gives us a tool for the non-empirical choice of the mixing coefficient under ambient and extreme conditions. Our analysis provides physical insights into the effect of the variation of the mixing coefficient in hybrid functionals, which is of immense practical value. The presented approach is general and can be used for other types of functionals like screened hybrids.

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“…In particular, the PIMC results have been used as the basis for a neural-net representation of the static electronic local field correction, and have become available as an analytical representation [69] that incorporates different limits [70]. In the mean time, these investigations have been extended to the nonlinear regime [41,[71][72][73][74][75], which, interestingly, is connected to the higher-order imaginary-time correlation functions [76].…”

Section: Introductionmentioning

confidence: 99%

Energy response and spatial alignment of the perturbed electron gas

Dornheim¹,

Tolias²,

Moldabekov³

et al. 2023

Preprint

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We present extensive new ab initio path integral Monte Carlo (PIMC) simulations of the harmonically perturbed uniform electron gas (UEG) for different densities and temperatures. This allows us to study the linear response of the UEG with respect to different contributions to the total energy for different wave numbers. We find that the induced change in the interaction energy exhibits a non-monotonic behaviour, and becomes negative for intermediate wave numbers. This effect is strongly dependent on the coupling strength and can be traced back to the spatial alignment of electrons introduced in earlier works [T. Dornheim et al., Communications Physics 5, 304 (2022)]. The observed quadratic dependence on the perturbation amplitude in the limit of weak perturbations and the quartic dependence of the perturbation amplitude corrections are consistent with linear and non-linear versions of the density stifness theorem. All PIMC simulation results are freely available online and can be used to benchmark new methods, or as input for other calculations.

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Thermal excitation signals in the inhomogeneous warm dense electron gas

Cited by 16 publications

References 87 publications

Nonlinear interaction of external perturbations in warm dense matter

Nonlinear interaction of external perturbations in warm dense matter

Non-empirical Mixing Coefficient for Hybrid XC Functionals from Analysis of the XC Kernel

Energy response and spatial alignment of the perturbed electron gas

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