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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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Moldabekov Z, Gawne TD, Schwalbe S, Preston TR, Vorberger J, Dornheim T. Ultrafast Heating-Induced Suppression of d-Band Dominance in the Electronic Excitation Spectrum of Cuprum. ACS OMEGA 2024; 9:25239-25250. [PMID: 38882083 PMCID: PMC11170750 DOI: 10.1021/acsomega.4c02920] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/26/2024] [Revised: 05/08/2024] [Accepted: 05/20/2024] [Indexed: 06/18/2024]
Abstract
The combination of isochoric heating of solids by free-electron lasers (FELs) and in situ diagnostics by X-ray Thomson scattering (XRTS) allows for measurements of material properties at warm dense matter (WDM) conditions relevant for astrophysics, inertial confinement fusion, and materials science. In the case of metals, the FEL beam pumps energy directly into electrons with the lattice structure of ions being nearly unaffected. This leads to a unique transient state that gives rise to a set of interesting physical effects, which can serve as a reliable testing platform for WDM theories. In this work, we present extensive linear-response time-dependent density functional theory (TDDFT) results for the electronic dynamic structure factor of isochorically heated copper with a face-centered cubic lattice. At ambient conditions, the plasmon is heavily damped due to the presence of d-band excitations, and its position is independent of the wavenumber. In contrast, the plasmon feature starts to dominate the excitation spectrum and has a Bohm-Gross-type plasmon dispersion for temperatures T ≥ 4 eV, where the quasi-free electrons in the interstitial region are in the WDM regime. In addition, we analyze the thermal changes in the d-band excitations and outline the possibility to use future XRTS measurements of isochorically heated copper as a controlled testbed for WDM theories.
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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
| | - Thomas D Gawne
- Center for Advanced Systems Understanding (CASUS), D-02826 Görlitz, Germany
- Helmholtz-Zentrum Dresden-Rossendorf (HZDR), D-01328 Dresden, Germany
| | - Sebastian Schwalbe
- 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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3
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Vu JP, Chen M. Noise reduction of stochastic density functional theory for metals. J Chem Phys 2024; 160:214125. [PMID: 38842491 DOI: 10.1063/5.0207244] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2024] [Accepted: 05/16/2024] [Indexed: 06/07/2024] Open
Abstract
Density Functional Theory (DFT) has become a cornerstone in the modeling of metals. However, accurately simulating metals, particularly under extreme conditions, presents two significant challenges. First, simulating complex metallic systems at low electron temperatures is difficult due to their highly delocalized density matrix. Second, modeling metallic warm-dense materials at very high electron temperatures is challenging because it requires the computation of a large number of partially occupied orbitals. This study demonstrates that both challenges can be effectively addressed using the latest advances in linear-scaling stochastic DFT methodologies. Despite the inherent introduction of noise into all computed properties by stochastic DFT, this research evaluates the efficacy of various noise reduction techniques under different thermal conditions. Our observations indicate that the effectiveness of noise reduction strategies varies significantly with the electron temperature. Furthermore, we provide evidence that the computational cost of stochastic DFT methods scales linearly with system size for metal systems, regardless of the electron temperature regime.
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Affiliation(s)
- Jake P Vu
- Department of Chemistry, Purdue University, West Lafayette, Indiana 47907, USA
| | - Ming Chen
- Department of Chemistry, Purdue University, West Lafayette, Indiana 47907, USA
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4
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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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5
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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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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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