1
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Dornheim T, Döppner T, Baczewski AD, Tolias P, Böhme MP, Moldabekov ZA, Gawne T, Ranjan D, Chapman DA, MacDonald MJ, Preston TR, Kraus D, Vorberger J. X-ray Thomson scattering absolute intensity from the f-sum rule in the imaginary-time domain. Sci Rep 2024; 14:14377. [PMID: 38909077 PMCID: PMC11193768 DOI: 10.1038/s41598-024-64182-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2024] [Accepted: 06/05/2024] [Indexed: 06/24/2024] Open
Abstract
We present a formally exact and simulation-free approach for the normalization of X-ray Thomson scattering (XRTS) spectra based on the f-sum rule of the imaginary-time correlation function (ITCF). Our method works for any degree of collectivity, over a broad range of temperatures, and is applicable even in nonequilibrium situations. In addition to giving us model-free access to electronic correlations, this new approach opens up the intriguing possibility to extract a plethora of physical properties from the ITCF based on XRTS experiments.
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Affiliation(s)
- T Dornheim
- Center for Advanced Systems Understanding (CASUS), 02826, Görlitz, Germany.
- Helmholtz-Zentrum Dresden-Rossendorf (HZDR), 01328, Dresden, Germany.
| | - T Döppner
- Lawrence Livermore National Laboratory (LLNL), California, 94550, Livermore, USA
| | - A D Baczewski
- Center for Computing Research, Sandia National Laboratories, Albuquerque, NM, 87185, USA
| | - P Tolias
- Space and Plasma Physics, Royal Institute of Technology (KTH), Stockholm, 100 44, Sweden
| | - M P Böhme
- Center for Advanced Systems Understanding (CASUS), 02826, Görlitz, Germany
- Helmholtz-Zentrum Dresden-Rossendorf (HZDR), 01328, Dresden, Germany
- Technische Universität Dresden, 01062, Dresden, Germany
| | - Zh A Moldabekov
- Center for Advanced Systems Understanding (CASUS), 02826, Görlitz, Germany
- Helmholtz-Zentrum Dresden-Rossendorf (HZDR), 01328, Dresden, Germany
| | - Th Gawne
- Center for Advanced Systems Understanding (CASUS), 02826, Görlitz, Germany
- Helmholtz-Zentrum Dresden-Rossendorf (HZDR), 01328, Dresden, Germany
| | - D Ranjan
- Institut für Physik, Universität Rostock, 18057, Rostock, Germany
| | - D A Chapman
- First Light Fusion, Yarnton, Oxfordshire, UK
| | - M J MacDonald
- Lawrence Livermore National Laboratory (LLNL), California, 94550, Livermore, USA
| | | | - D Kraus
- Institut für Physik, Universität Rostock, 18057, Rostock, Germany
| | - J Vorberger
- Helmholtz-Zentrum Dresden-Rossendorf (HZDR), 01328, Dresden, Germany
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2
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Dornheim T, Schwalbe S, Moldabekov ZA, Vorberger J, Tolias P. Ab Initio Path Integral Monte Carlo Simulations of the Uniform Electron Gas on Large Length Scales. J Phys Chem Lett 2024; 15:1305-1313. [PMID: 38285536 PMCID: PMC10860150 DOI: 10.1021/acs.jpclett.3c03193] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2023] [Revised: 01/17/2024] [Accepted: 01/22/2024] [Indexed: 01/31/2024]
Abstract
The accurate description of non-ideal quantum many-body systems is of prime importance for a host of applications within physics, quantum chemistry, materials science, and related disciplines. At finite temperatures, the gold standard is given by ab initio path integral Monte Carlo (PIMC) simulations, which do not require any empirical input but exhibit an exponential increase in the required computation time for Fermionic systems with an increase in system size N. Very recently, computing Fermionic properties without this bottleneck based on PIMC simulations of fictitious identical particles has been suggested. In our work, we use this technique to perform very large (N ≤ 1000) PIMC simulations of the warm dense electron gas and demonstrate that it is capable of providing a highly accurate description of the investigated properties, i.e., the static structure factor, the static density response function, and the local field correction, over the entire range of length scales.
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Affiliation(s)
- Tobias Dornheim
- Center
for Advanced Systems Understanding (CASUS), Helmholtz-Zentrum Dresden-Rossendorf (HZDR), D-02826 Görlitz, Germany
| | - Sebastian Schwalbe
- Center
for Advanced Systems Understanding (CASUS), Helmholtz-Zentrum Dresden-Rossendorf (HZDR), D-02826 Görlitz, Germany
| | - Zhandos A. Moldabekov
- Center
for Advanced Systems Understanding (CASUS), Helmholtz-Zentrum Dresden-Rossendorf (HZDR), D-02826 Görlitz, Germany
| | - Jan Vorberger
- Institute
of Radiation Physics, Helmholtz-Zentrum
Dresden-Rossendorf (HZDR), D-01328 Dresden, Germany
| | - Panagiotis Tolias
- Space
and Plasma Physics, Royal Institute of Technology
(KTH), Stockholm SE-100 44, Sweden
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3
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Dornheim T, Tolias P, Groth S, Moldabekov ZA, Vorberger J, Hirshberg B. Fermionic physics from ab initio path integral Monte Carlo simulations of fictitious identical particles. J Chem Phys 2023; 159:164113. [PMID: 37888764 DOI: 10.1063/5.0171930] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2023] [Accepted: 10/06/2023] [Indexed: 10/28/2023] Open
Abstract
The ab initio path integral Monte Carlo (PIMC) method is one of the most successful methods in statistical physics, quantum chemistry and related fields, but its application to quantum degenerate Fermi systems is severely hampered by an exponential computational bottleneck: the notorious fermion sign problem. Very recently, Xiong and Xiong [J. Chem. Phys. 157, 094112 (2022)] have suggested to partially circumvent the sign problem by carrying out simulations of fictitious systems guided by an interpolating continuous variable ξ ∈ [-1, 1], with the physical Fermi- and Bose-statistics corresponding to ξ = -1 and ξ = 1. It has been proposed that information about the fermionic limit might be obtained by calculations within the bosonic sector ξ > 0 combined with an extrapolation throughout the fermionic sector ξ < 0, essentially bypassing the sign problem. Here, we show how the inclusion of the artificial parameter ξ can be interpreted as an effective penalty on the formation of permutation cycles in the PIMC simulation. We demonstrate that the proposed extrapolation method breaks down for moderate to high quantum degeneracy. Instead, the method constitutes a valuable tool for the description of large Fermi-systems of weak quantum degeneracy. This is demonstrated for electrons in a 2D harmonic trap and for the uniform electron gas (UEG), where we find excellent agreement (∼0.5%) with exact configuration PIMC results in the high-density regime while attaining a speed-up exceeding 11 orders of magnitude. Finally, we extend the idea beyond the energy and analyze the radial density distribution (2D trap), as well as the static structure factor and imaginary-time density-density correlation function (UEG).
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Affiliation(s)
- Tobias Dornheim
- Center for Advanced Systems Understanding (CASUS), D-02826 Görlitz, Germany
- Helmholtz-Zentrum Dresden-Rossendorf (HZDR), D-01328 Dresden, Germany
| | - Panagiotis Tolias
- Space and Plasma Physics, Royal Institute of Technology (KTH), Stockholm SE-100 44, Sweden
| | - Simon Groth
- Christian-Albrechts-Universität zu Kiel, D-24098 Kiel, Germany
| | - Zhandos A Moldabekov
- Center for Advanced Systems Understanding (CASUS), D-02826 Görlitz, Germany
- Helmholtz-Zentrum Dresden-Rossendorf (HZDR), D-01328 Dresden, Germany
| | - Jan Vorberger
- Helmholtz-Zentrum Dresden-Rossendorf (HZDR), D-01328 Dresden, Germany
| | - Barak Hirshberg
- School of Chemistry, Tel Aviv University, Tel Aviv 6997801, Israel
- The Center for Computational Molecular and Materials Science, Tel Aviv University, Tel Aviv 6997801, Israel
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4
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Dornheim T, Böhme MP, Moldabekov ZA, Vorberger J. Electronic density response of warm dense hydrogen on the nanoscale. Phys Rev E 2023; 108:035204. [PMID: 37849144 DOI: 10.1103/physreve.108.035204] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2023] [Accepted: 08/11/2023] [Indexed: 10/19/2023]
Abstract
The properties of hydrogen at warm dense matter (WDM) conditions are of high importance for the understanding of astrophysical objects and technological applications such as inertial confinement fusion. In this work, we present extensive ab initio path integral Monte Carlo results for the electronic properties in the Coulomb potential of a fixed ionic configuration. This gives us unique insights into the complex interplay between the electronic localization around the protons with their density response to an external harmonic perturbation. We find qualitative agreement between our simulation data and a heuristic model based on the assumption of a local uniform electron gas model, but important trends are not captured by this simplification. In addition to being interesting in their own right, we are convinced that our results will be of high value for future projects, such as the rigorous benchmarking of approximate theories for the simulation of WDM, most notably density functional theory.
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Affiliation(s)
- Tobias Dornheim
- Center for Advanced Systems Understanding (CASUS), D-02826 Görlitz, Germany
- Helmholtz-Zentrum Dresden-Rossendorf (HZDR), D-01328 Dresden, Germany
| | - Maximilian P Böhme
- Center for Advanced Systems Understanding (CASUS), D-02826 Görlitz, Germany
- Helmholtz-Zentrum Dresden-Rossendorf (HZDR), D-01328 Dresden, Germany
- Technische Universität Dresden, D-01062 Dresden, Germany
| | - Zhandos A Moldabekov
- Center for Advanced Systems Understanding (CASUS), D-02826 Görlitz, Germany
- Helmholtz-Zentrum Dresden-Rossendorf (HZDR), D-01328 Dresden, Germany
| | - Jan Vorberger
- Helmholtz-Zentrum Dresden-Rossendorf (HZDR), D-01328 Dresden, Germany
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5
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Dornheim T, Vorberger J, Moldabekov ZA, Böhme M. Analysing the dynamic structure of warm dense matter in the imaginary-time domain: theoretical models and simulations. PHILOSOPHICAL TRANSACTIONS. SERIES A, MATHEMATICAL, PHYSICAL, AND ENGINEERING SCIENCES 2023; 381:20220217. [PMID: 37393936 DOI: 10.1098/rsta.2022.0217] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/04/2022] [Accepted: 01/10/2023] [Indexed: 07/04/2023]
Abstract
Rigorous diagnostics of experiments with warm dense matter are notoriously difficult. A key method is X-ray Thomson scattering (XRTS), but the interpretation of XRTS measurements is usually based on theoretical models that entail various approximations. Recently, Dornheim et al. [Nat. Commun. 13, 7911 (2022)] introduced a new framework for temperature diagnostics of XRTS experiments that is based on imaginary-time correlation functions. On the one hand, switching from the frequency to the imaginary-time domain gives one direct access to a number of physical properties, which facilitates the extraction of the temperature of arbitrarily complex materials without relying on any models or approximations. On the other hand, the bulk of theoretical work in dynamic quantum many-body theory is devoted to the frequency domain, and, to the best of our knowledge, the manifestation of physics properties within the imaginary-time density-density correlation function (ITCF) remains poorly understood. In the present work, we aim to fill this gap by introducing a simple, semi-analytical model for the imaginary-time dependence of two-body correlations within the framework of imaginary-time path integrals. As a practical example, we compare our new model to extensive ab initio path integral Monte Carlo results for the ITCF of a uniform electron gas, and find excellent agreement over a broad range of wavenumbers, densities and temperatures. This article is part of the theme issue 'Dynamic and transient processes in warm dense matter'.
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Affiliation(s)
- Tobias Dornheim
- Center for Advanced Systems Understanding (CASUS), D-02826 Görlitz, Germany
- Helmholtz-Zentrum Dresden-Rossendorf (HZDR), D-01328 Dresden, Germany
| | - Jan Vorberger
- Helmholtz-Zentrum Dresden-Rossendorf (HZDR), D-01328 Dresden, Germany
| | - Zhandos A Moldabekov
- Center for Advanced Systems Understanding (CASUS), D-02826 Görlitz, Germany
- Helmholtz-Zentrum Dresden-Rossendorf (HZDR), D-01328 Dresden, Germany
| | - Maximilian Böhme
- Center for Advanced Systems Understanding (CASUS), D-02826 Görlitz, Germany
- Helmholtz-Zentrum Dresden-Rossendorf (HZDR), D-01328 Dresden, Germany
- Technische Universität Dresden, D-01062 Dresden, Germany
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6
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Tolias P, Lucco Castello F, Dornheim T. Quantum version of the integral equation theory-based dielectric scheme for strongly coupled electron liquids. J Chem Phys 2023; 158:141102. [PMID: 37061474 DOI: 10.1063/5.0145687] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/17/2023] Open
Abstract
A novel dielectric scheme is proposed for strongly coupled electron liquids, which handles quantum mechanical effects beyond the random phase approximation level and treats electronic correlations within the integral equation theory of classical liquids. The self-consistent scheme features a complicated dynamic local field correction functional and its formulation is guided by ab initio path integral Monte Carlo simulations. Remarkably, our scheme is capable of providing unprecedently accurate results for the static structure factor with the exception of the Wigner crystallization vicinity, despite the absence of adjustable or empirical parameters.
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Affiliation(s)
- Panagiotis Tolias
- Space and Plasma Physics - Royal Institute of Technology (KTH), SE-10044 Stockholm, Sweden
| | | | - Tobias Dornheim
- Center for Advanced Systems Understanding (CASUS), D-02826 Görlitz, Germany
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7
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Moldabekov ZA, Lokamani M, Vorberger J, Cangi A, Dornheim T. Assessing the accuracy of hybrid exchange-correlation functionals for the density response of warm dense electrons. J Chem Phys 2023; 158:094105. [PMID: 36889956 DOI: 10.1063/5.0135729] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
We assess the accuracy of common hybrid exchange-correlation (XC) functionals (PBE0, PBE0-1/3, HSE06, HSE03, and B3LYP) within the Kohn-Sham density functional theory for the harmonically perturbed electron gas at parameters relevant for the challenging conditions of the warm dense matter. Generated by laser-induced compression and heating in the laboratory, the warm dense matter is a state of matter that also occurs in white dwarfs and planetary interiors. We consider both weak and strong degrees of density inhomogeneity induced by the external field at various wavenumbers. We perform an error analysis by comparing with the exact quantum Monte Carlo results. In the case of a weak perturbation, we report the static linear density response function and the static XC kernel at a metallic density for both the degenerate ground-state limit and for partial degeneracy at the electronic Fermi temperature. Overall, we observe an improvement in the density response when the PBE0, PBE0-1/3, HSE06, and HSE03 functionals are used, compared with the previously reported results for the PBE, PBEsol, local-density approximation, and AM05 functionals; B3LYP, on the other hand, does not perform well for the considered system. Additionally, the PBE0, PBE0-1/3, HSE06, and HSE03 functionals are more accurate for the density response properties than SCAN in the regime of partial degeneracy.
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Affiliation(s)
- Zhandos A Moldabekov
- Center for Advanced Systems Understanding (CASUS), Helmholtz-Zentrum Dresden-Rossendorf (HZDR), D-02826 Görlitz, Germany
| | - Mani Lokamani
- Information Services and Computing, Helmholtz-Zentrum Dresden-Rossendorf (HZDR), D-01328 Dresden, Germany
| | - Jan Vorberger
- Insitute of Radiation Physics, Helmholtz-Zentrum Dresden-Rossendorf (HZDR), D-01328 Dresden, Germany
| | - Attila Cangi
- Center for Advanced Systems Understanding (CASUS), Helmholtz-Zentrum Dresden-Rossendorf (HZDR), D-02826 Görlitz, Germany
| | - Tobias Dornheim
- Center for Advanced Systems Understanding (CASUS), Helmholtz-Zentrum Dresden-Rossendorf (HZDR), D-02826 Görlitz, Germany
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8
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Moldabekov ZA, Lokamani M, Vorberger J, Cangi A, Dornheim T. Non-empirical Mixing Coefficient for Hybrid XC Functionals from Analysis of the XC Kernel. J Phys Chem Lett 2023; 14:1326-1333. [PMID: 36724891 PMCID: PMC9923747 DOI: 10.1021/acs.jpclett.2c03670] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2022] [Accepted: 01/13/2023] [Indexed: 06/18/2023]
Abstract
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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Affiliation(s)
- Zhandos A. Moldabekov
- Center
for Advanced Systems Understanding (CASUS), Helmholtz-Zentrum Dresden-Rossendorf (HZDR), D-02826Görlitz, Germany
| | - Mani Lokamani
- Information
Services and Computing, Helmholtz-Zentrum
Dresden-Rossendorf (HZDR), D-01328Dresden, Germany
| | - Jan Vorberger
- Institute
of Radiation Physics, Helmholtz-Zentrum
Dresden-Rossendorf (HZDR), D-01328Dresden, Germany
| | - Attila Cangi
- Center
for Advanced Systems Understanding (CASUS), Helmholtz-Zentrum Dresden-Rossendorf (HZDR), D-02826Görlitz, Germany
| | - Tobias Dornheim
- Center
for Advanced Systems Understanding (CASUS), Helmholtz-Zentrum Dresden-Rossendorf (HZDR), D-02826Görlitz, Germany
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9
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Moldabekov Z, Böhme M, Vorberger J, Blaschke D, Dornheim T. Ab Initio Static Exchange-Correlation Kernel across Jacob's Ladder without Functional Derivatives. J Chem Theory Comput 2023; 19:1286-1299. [PMID: 36724889 PMCID: PMC9979610 DOI: 10.1021/acs.jctc.2c01180] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
The electronic exchange─correlation (XC) kernel constitutes a fundamental input for the estimation of a gamut of properties such as the dielectric characteristics, the thermal and electrical conductivity, or the response to an external perturbation. In this work, we present a formally exact methodology for the computation of the system specific static XC kernel exclusively within the framework of density functional theory (DFT) and without employing functional derivatives─no external input apart from the usual XC-functional is required. We compare our new results with exact quantum Monte Carlo (QMC) data for the archetypical uniform electron gas model under both ambient and warm dense matter conditions. This gives us unprecedented insights into the performance of different XC functionals, and it has important implications for the development of new functionals that are designed for the application at extreme temperatures. In addition, we obtain new DFT results for the XC kernel of warm dense hydrogen as it occurs in fusion applications and astrophysical objects. The observed excellent agreement to the QMC reference data demonstrates that presented framework is capable to capture nontrivial effects such as XC-induced isotropy breaking in the density response of hydrogen at large wave numbers.
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Affiliation(s)
- Zhandos Moldabekov
- Center
for Advanced Systems Understanding (CASUS), D-02826Görlitz, Germany,Helmholtz-Zentrum
Dresden-Rossendorf (HZDR), D-01328Dresden, Germany,E-mail:
| | - Maximilian Böhme
- Center
for Advanced Systems Understanding (CASUS), D-02826Görlitz, Germany
| | - Jan Vorberger
- Helmholtz-Zentrum
Dresden-Rossendorf (HZDR), D-01328Dresden, Germany
| | - David Blaschke
- Institute
of Theoretical Physics, University of Wroclaw, 50-204Wroclaw, Poland
| | - Tobias Dornheim
- Center
for Advanced Systems Understanding (CASUS), D-02826Görlitz, Germany,Helmholtz-Zentrum
Dresden-Rossendorf (HZDR), D-01328Dresden, Germany,E-mail:
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10
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Dornheim T, Böhme M, Kraus D, Döppner T, Preston TR, Moldabekov ZA, Vorberger J. Accurate temperature diagnostics for matter under extreme conditions. Nat Commun 2022; 13:7911. [PMID: 36564411 PMCID: PMC9789064 DOI: 10.1038/s41467-022-35578-7] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2022] [Accepted: 12/12/2022] [Indexed: 12/24/2022] Open
Abstract
The experimental investigation of matter under extreme densities and temperatures, as in astrophysical objects and nuclear fusion applications, constitutes one of the most active frontiers at the interface of material science, plasma physics, and engineering. The central obstacle is given by the rigorous interpretation of the experimental results, as even the diagnosis of basic parameters like the temperature T is rendered difficult at these extreme conditions. Here, we present a simple, approximation-free method to extract the temperature of arbitrarily complex materials in thermal equilibrium from X-ray Thomson scattering experiments, without the need for any simulations or an explicit deconvolution. Our paradigm can be readily implemented at modern facilities and corresponding experiments will have a profound impact on our understanding of warm dense matter and beyond, and open up a variety of appealing possibilities in the context of thermonuclear fusion, laboratory astrophysics, and related disciplines.
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Affiliation(s)
- Tobias Dornheim
- grid.510908.5Center for Advanced Systems Understanding (CASUS), Görlitz, D-02826 Germany ,grid.40602.300000 0001 2158 0612Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Dresden, D-01328 Germany
| | - Maximilian Böhme
- grid.510908.5Center for Advanced Systems Understanding (CASUS), Görlitz, D-02826 Germany ,grid.40602.300000 0001 2158 0612Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Dresden, D-01328 Germany ,grid.4488.00000 0001 2111 7257Technische Universität Dresden, Dresden, D-01062 Germany
| | - Dominik Kraus
- grid.40602.300000 0001 2158 0612Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Dresden, D-01328 Germany ,grid.10493.3f0000000121858338Institut für Physik, Universität Rostock, Rostock, D-18059 Germany
| | - Tilo Döppner
- grid.250008.f0000 0001 2160 9702Lawrence Livermore National Laboratory, Livermore, CA 94550 USA
| | - Thomas R. Preston
- grid.434729.f0000 0004 0590 2900European XFEL, Schenefeld, D-22869 Germany
| | - Zhandos A. Moldabekov
- grid.510908.5Center for Advanced Systems Understanding (CASUS), Görlitz, D-02826 Germany ,grid.40602.300000 0001 2158 0612Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Dresden, D-01328 Germany
| | - Jan Vorberger
- grid.40602.300000 0001 2158 0612Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Dresden, D-01328 Germany
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11
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Dornheim T, Tolias P, Moldabekov ZA, Cangi A, Vorberger J. Effective electronic forces and potentials from ab initio path integral Monte Carlo simulations. J Chem Phys 2022; 156:244113. [PMID: 35778089 DOI: 10.1063/5.0097768] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The rigorous description of correlated quantum many-body systems constitutes one of the most challenging tasks in contemporary physics and related disciplines. In this context, a particularly useful tool is the concept of effective pair potentials that take into account the effects of the complex many-body medium consistently. In this work, we present extensive, highly accurate ab initio path integral Monte Carlo (PIMC) results for the effective interaction and the effective force between two electrons in the presence of the uniform electron gas. This gives us a direct insight into finite-size effects, thereby, opening up the possibility for novel domain decompositions and methodological advances. In addition, we present unassailable numerical proof for an effective attraction between two electrons under moderate coupling conditions, without the mediation of an underlying ionic structure. Finally, we compare our exact PIMC results to effective potentials from linear-response theory, and we demonstrate their usefulness for the description of the dynamic structure factor. All PIMC results are made freely available online and can be used as a thorough benchmark for new developments and approximations.
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Affiliation(s)
- Tobias Dornheim
- Center for Advanced Systems Understanding (CASUS), D-02826 Görlitz, Germany
| | - Panagiotis Tolias
- Space and Plasma Physics, Royal Institute of Technology (KTH), Stockholm SE-100 44, Sweden
| | | | - Attila Cangi
- Center for Advanced Systems Understanding (CASUS), D-02826 Görlitz, Germany
| | - Jan Vorberger
- Helmholtz-Zentrum Dresden-Rossendorf (HZDR), D-01328 Dresden, Germany
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12
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Moldabekov Z, Vorberger J, Dornheim T. Density Functional Theory Perspective on the Nonlinear Response of Correlated Electrons across Temperature Regimes. J Chem Theory Comput 2022; 18:2900-2912. [PMID: 35484932 PMCID: PMC9097288 DOI: 10.1021/acs.jctc.2c00012] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
We explore a new formalism to study the nonlinear electronic density response based on Kohn-Sham density functional theory (KS-DFT) at partially and strongly quantum degenerate regimes. It is demonstrated that the KS-DFT calculations are able to accurately reproduce the available path integral Monte Carlo simulation results at temperatures relevant for warm dense matter research. The existing analytical results for the quadratic and cubic response functions are rigorously tested. It is demonstrated that the analytical results for the quadratic response function closely agree with the KS-DFT data. Furthermore, the performed analysis reveals that currently available analytical formulas for the cubic response function are not able to describe simulation results, neither qualitatively nor quantitatively, at small wavenumbers q < 2qF, with qF being the Fermi wavenumber. The results show that KS-DFT can be used to describe warm dense matter that is strongly perturbed by an external field with remarkable accuracy. Furthermore, it is demonstrated that KS-DFT constitutes a valuable tool to guide the development of the nonlinear response theory of correlated quantum electrons from ambient to extreme conditions. This opens up new avenues to study nonlinear effects in a gamut of different contexts at conditions that cannot be accessed with previously used path integral Monte Carlo methods.
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Affiliation(s)
- Zhandos Moldabekov
- Center for Advanced Systems Understanding (CASUS), D-02826 Görlitz, Germany.,Helmholtz-Zentrum Dresden-Rossendorf (HZDR), D-01328 Dresden, Germany
| | - Jan Vorberger
- Helmholtz-Zentrum Dresden-Rossendorf (HZDR), D-01328 Dresden, Germany
| | - Tobias Dornheim
- Center for Advanced Systems Understanding (CASUS), D-02826 Görlitz, Germany.,Helmholtz-Zentrum Dresden-Rossendorf (HZDR), D-01328 Dresden, Germany
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13
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Demyanov GS, Knyazev DV, Levashov PR. Continuous Kubo-Greenwood formula: Theory and numerical implementation. Phys Rev E 2022; 105:035307. [PMID: 35428130 DOI: 10.1103/physreve.105.035307] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2021] [Accepted: 03/02/2022] [Indexed: 06/14/2023]
Abstract
In this paper, we present the so-called continuous Kubo-Greenwood formula intended for the numerical calculation of the dynamic Onsager coefficients and, in particular, the real part of dynamic electrical conductivity. In contrast to the usual Kubo-Greenwood formula, which contains the summation over a discrete set of transitions between electron energy levels, the continuous one is formulated as an integral over the whole energy range. This integral includes the continuous functions: the smoothed squares of matrix elements, D(ɛ,ɛ+ℏω), the densities of state, g(ɛ)g(ɛ+ℏω), and the difference of the Fermi weights, [f(ɛ)-f(ɛ+ℏω)]/(ℏω). The function D(ɛ,ɛ+ℏω) is obtained via the specially developed smoothing procedure. From the theoretical point of view, the continuous formula is an alternative to the usual one. Both can be used to calculate matter properties and produce close results. However, the continuous formula includes the smooth functions that can be plotted and examined. Thus, we can analyze the contributions of various parts of the electron spectrum to the obtained properties. The possibility of such analysis is the main advantage of the continuous formula. The continuous Kubo-Greenwood formula is implemented in the parallel code cubogram. Using the code we demonstrate the influence of technical parameters on the simulation results for liquid aluminum. We also analyze various methods of matrix elements computation and their effect on dynamic electrical conductivity.
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Affiliation(s)
- G S Demyanov
- Joint Institute for High Temperatures, Izhorskaya 13 Building 2, Moscow 125412, Russia and Moscow Institute of Physics and Technology, Institutskiy Pereulok 9, Dolgoprudny, Moscow Region 141700, Russia
| | - D V Knyazev
- Joint Institute for High Temperatures, Izhorskaya 13 Building 2, Moscow 125412, Russia and Moscow Institute of Physics and Technology, Institutskiy Pereulok 9, Dolgoprudny, Moscow Region 141700, Russia
| | - P R Levashov
- Joint Institute for High Temperatures, Izhorskaya 13 Building 2, Moscow 125412, Russia and Moscow Institute of Physics and Technology, Institutskiy Pereulok 9, Dolgoprudny, Moscow Region 141700, Russia
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14
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Thermal excitation signals in the inhomogeneous warm dense electron gas. Sci Rep 2022; 12:1093. [PMID: 35058531 PMCID: PMC8776784 DOI: 10.1038/s41598-022-05034-z] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2021] [Accepted: 12/30/2021] [Indexed: 12/16/2022] Open
Abstract
We investigate the emergence of electronic excitations from the inhomogeneous electronic structure at warm dense matter parameters based on first-principles calculations. The emerging modes are controlled by the imposed perturbation amplitude. They include satellite signals around the standard plasmon feature, transformation of plasmons to optical modes, and double-plasmon modes. These modes exhibit a pronounced dependence on the temperature. This makes them potentially invaluable for the diagnostics of plasma parameters in the warm dense matter regime. We demonstrate that these modes can be probed with present experimental techniques.
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15
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Dornheim T, Vorberger J, Militzer B, Moldabekov ZA. Momentum distribution of the uniform electron gas at finite temperature: Effects of spin polarization. Phys Rev E 2021; 104:055206. [PMID: 34942706 DOI: 10.1103/physreve.104.055206] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2021] [Accepted: 10/25/2021] [Indexed: 11/07/2022]
Abstract
We carry out extensive direct path integral Monte Carlo (PIMC) simulations of the uniform electron gas (UEG) at finite temperature for different values of the spin-polarization ξ. This allows us to unambiguously quantify the impact of spin effects on the momentum distribution function n(k) and related properties. We find that interesting physical effects like the interaction-induced increase in the occupation of the zero-momentum state n(0) substantially depend on ξ. Our results further advance the current understanding of the UEG as a fundamental model system, and are of practical relevance for the description of transport properties of warm dense matter in an external magnetic field. All PIMC results are freely available online and can be used as a benchmark for the development of methods and applications.
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Affiliation(s)
- Tobias Dornheim
- Center for Advanced Systems Understanding (CASUS), D-02826 Görlitz, Germany.,Helmholtz-Zentrum Dresden-Rossendorf (HZDR), D-01328 Dresden, Germany
| | - Jan Vorberger
- Helmholtz-Zentrum Dresden-Rossendorf (HZDR), D-01328 Dresden, Germany
| | - Burkhard Militzer
- Department of Earth and Planetary Science, University of California, Berkeley, California 94720, USA.,Department of Astronomy, University of California, Berkeley, California 94720, USA
| | - Zhandos A Moldabekov
- Center for Advanced Systems Understanding (CASUS), D-02826 Görlitz, Germany.,Helmholtz-Zentrum Dresden-Rossendorf (HZDR), D-01328 Dresden, Germany
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16
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Tolias P, Lucco Castello F, Dornheim T. Integral equation theory based dielectric scheme for strongly coupled electron liquids. J Chem Phys 2021; 155:134115. [PMID: 34625000 DOI: 10.1063/5.0065988] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
In a recent paper, Lucco Castello et al. (arXiv:2107.03537) provided an accurate parameterization of classical one-component plasma bridge functions that was embedded in a novel dielectric scheme for strongly coupled electron liquids. Here, this approach is rigorously formulated, its set of equations is formally derived, and its numerical algorithm is scrutinized. A systematic comparison with available and new path integral Monte Carlo simulations reveals a rather unprecedented agreement especially in terms of the interaction energy and the long wavelength limit of the static local field correction.
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Affiliation(s)
- P Tolias
- Space and Plasma Physics-Royal Institute of Technology (KTH), SE-10044 Stockholm, Sweden
| | - F Lucco Castello
- Space and Plasma Physics-Royal Institute of Technology (KTH), SE-10044 Stockholm, Sweden
| | - T Dornheim
- Center for Advanced Systems Understanding (CASUS), D-02826 Görlitz, Germany
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17
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Moldabekov Z, Dornheim T, Böhme M, Vorberger J, Cangi A. The relevance of electronic perturbations in the warm dense electron gas. J Chem Phys 2021; 155:124116. [PMID: 34598570 DOI: 10.1063/5.0062325] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Warm dense matter (WDM) has emerged as one of the frontiers of both experimental physics and theoretical physics and is a challenging traditional concept of plasma, atomic, and condensed-matter physics. While it has become common practice to model correlated electrons in WDM within the framework of Kohn-Sham density functional theory, quantitative benchmarks of exchange-correlation (XC) functionals under WDM conditions are yet incomplete. Here, we present the first assessment of common XC functionals against exact path-integral Monte Carlo calculations of the harmonically perturbed thermal electron gas. This system is directly related to the numerical modeling of x-ray scattering experiments on warm dense samples. Our assessment yields the parameter space where common XC functionals are applicable. More importantly, we pinpoint where the tested XC functionals fail when perturbations on the electronic structure are imposed. We indicate the lack of XC functionals that take into account the needs of WDM physics in terms of perturbed electronic structures.
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Affiliation(s)
- Zhandos Moldabekov
- Center for Advanced Systems Understanding (CASUS), D-02826 Görlitz, Germany
| | - Tobias Dornheim
- Center for Advanced Systems Understanding (CASUS), D-02826 Görlitz, Germany
| | - Maximilian Böhme
- Center for Advanced Systems Understanding (CASUS), D-02826 Görlitz, Germany
| | - Jan Vorberger
- Helmholtz-Zentrum Dresden-Rossendorf (HZDR), D-01328 Dresden, Germany
| | - Attila Cangi
- Center for Advanced Systems Understanding (CASUS), D-02826 Görlitz, Germany
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18
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Zan X, Lin C, Hou Y, Yuan J. Local field correction to ionization potential depression of ions in warm or hot dense matter. Phys Rev E 2021; 104:025203. [PMID: 34525605 DOI: 10.1103/physreve.104.025203] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2021] [Accepted: 07/19/2021] [Indexed: 11/07/2022]
Abstract
An analytical self-consistent approach was recently established to predict the ionization potential depression (IPD) in multicomponent dense plasmas, which is achieved by considering the self-energy of ions and electrons within the quantum statistical theory. In order to explicitly account for the exchange-correlation effect of electrons, we incorporate the effective static approximation of local field correction (LFC) within our IPD framework through the connection of dynamical structure factor. The effective static approximation poses an accurate description for the asymptotic large wave number behavior with the recently developed machine learning representation of static LFC induced from the path-integral Monte Carlo data. Our calculation shows that the introduction of static LFC through dynamical structure factor brings a nontrivial influence on IPD at warm/hot dense matter conditions. The correlation effect within static LFC could provide up to 20% correction to free-electron contribution of IPD in the strong coupling and degeneracy regime. Furthermore, a new screening factor is obtained from the density distribution of free electrons calculated within the average-atom model, with which excellent agreements are observed with other methods and experiments at warm/hot dense matter conditions.
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Affiliation(s)
- Xiaolei Zan
- Department of Physics, College of Liberal Arts and Sciences, National University of Defense Technology, Changsha, Hunan 410073, People's Republic of China
| | - Chengliang Lin
- Graduate School of China Academy of Engineering Physics, Beijing 100193, People's Republic of China
| | - Yong Hou
- Department of Physics, College of Liberal Arts and Sciences, National University of Defense Technology, Changsha, Hunan 410073, People's Republic of China
| | - Jianmin Yuan
- Department of Physics, College of Liberal Arts and Sciences, National University of Defense Technology, Changsha, Hunan 410073, People's Republic of China.,Graduate School of China Academy of Engineering Physics, Beijing 100193, People's Republic of China
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19
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Hunger K, Schoof T, Dornheim T, Bonitz M, Filinov A. Momentum distribution function and short-range correlations of the warm dense electron gas: Ab initio quantum Monte Carlo results. Phys Rev E 2021; 103:053204. [PMID: 34134307 DOI: 10.1103/physreve.103.053204] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2021] [Accepted: 03/19/2021] [Indexed: 01/22/2023]
Abstract
In a classical plasma the momentum distribution, n(k), decays exponentially, for large k, and the same is observed for an ideal Fermi gas. However, when quantum and correlation effects are relevant simultaneously, an algebraic decay, n_{∞}(k)∼k^{-8} has been predicted. This is of relevance for cross sections and threshold processes in dense plasmas that depend on the number of energetic particles. Here we present extensive ab initio results for the momentum distribution of the nonideal uniform electron gas at warm dense matter conditions. Our results are based on first principle fermionic path integral Monte Carlo (CPIMC) simulations and clearly confirm the k^{-8} asymptotic. This asymptotic behavior is directly linked to short-range correlations which are analyzed via the on-top pair distribution function (on-top PDF), i.e., the PDF of electrons with opposite spin. We present extensive results for the density and temperature dependence of the on-top PDF and for the momentum distribution in the entire momentum range.
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Affiliation(s)
- Kai Hunger
- Institut für Theoretische Physik und Astrophysik, Christian-Albrechts-Universität zu Kiel, Leibnizstraße 15, 24098 Kiel, Germany
| | - Tim Schoof
- Institut für Theoretische Physik und Astrophysik, Christian-Albrechts-Universität zu Kiel, Leibnizstraße 15, 24098 Kiel, Germany.,Deutsches Elektronen Synchotron (DESY), Hamburg, Germany
| | - Tobias Dornheim
- Center for Advanced Systems Understanding (CASUS), D-02826 Görlitz, Germany.,Helmholtz-Zentrum Dresden-Rossendorf (HZDR), D-01328 Dresden, Germany
| | - Michael Bonitz
- Institut für Theoretische Physik und Astrophysik, Christian-Albrechts-Universität zu Kiel, Leibnizstraße 15, 24098 Kiel, Germany
| | - Alexey Filinov
- Institut für Theoretische Physik und Astrophysik, Christian-Albrechts-Universität zu Kiel, Leibnizstraße 15, 24098 Kiel, Germany.,Joint Institute for High Temperatures, Russian Academy of Sciences, Izhorskaya 13, Moscow 125412, Russia
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20
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Dornheim T, Vorberger J. Overcoming finite-size effects in electronic structure simulations at extreme conditions. J Chem Phys 2021; 154:144103. [DOI: 10.1063/5.0045634] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Tobias Dornheim
- Center for Advanced Systems Understanding (CASUS), D-02826 Görlitz, Germany
- Helmholtz-Zentrum Dresden-Rossendorf (HZDR), D-01328 Dresden, Germany
| | - Jan Vorberger
- Helmholtz-Zentrum Dresden-Rossendorf (HZDR), D-01328 Dresden, Germany
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