Observing the onset of pressure-driven K-shell delocalization

Döppner, T.; Bethkenhagen, Mandy; Kraus, D.; Neumayer, P.; Chapman, D. A.; Bachmann, B.; Baggott, R. A.; Böhme, Maximilian; Divol, L.; Falcone, R. W.; Fletcher, L. B.; Landen, O. L.; Saunders, A. M.; Schörner, Maximilian; Sterne, P. A.; Vorberger, Jan; Witte, B. B. L.; Yi, A.; Redmer, R.; Glenzer, S. H.; Gericke, Dirk O.

doi:10.1038/s41586-023-05996-8

Cited by 30 publications

(15 citation statements)

References 51 publications

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“…Checking the capability of the RDG to capture the nontrivial superposition of different charge states thus constitutes a natural follow-up project of this work. Indeed, this line of thought might, for example, help to shine light onto the delocalization of atomic orbitals in Be at extreme temperature and density that has very recently been observed by Döppner et al at the NIF.…”

Section: Discussionmentioning

confidence: 82%

“…From Figure 5 , we see that the quality of the RDG from thermal KS-DFT with the thermal LDA and ground-state SCAN functionals is extremely good at r s = 2. This is relevant information for WDM research since WDM is often generated using metals 71 in experiments. Interestingly, the quality of the analyzed thermal KS-DFT results for the RDG is somewhat worse at r s = 1 compared to r s = 2 despite the significantly less pronounced electronic structure in this regime.…”

Section: Resultsmentioning

confidence: 99%

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Bound-State Breaking and the Importance of Thermal Exchange–Correlation Effects in Warm Dense Hydrogen

Moldabekov,

Schwalbe,

Böhme

et al. 2023

J. Chem. Theory Comput.

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Hydrogen at extreme temperatures and pressures is of key relevance for cutting-edge technological applications, with inertial confinement fusion research being a prime example. In addition, it is ubiquitous throughout our universe and naturally occurs in a variety of astrophysical objects. In the present work, we present exact ab initio path integral Monte Carlo (PIMC) results for the electronic density of warm dense hydrogen along a line of constant degeneracy across a broad range of densities. Using the well-known concept of reduced density gradients, we develop a new framework to identify the breaking of bound states due to pressure ionization in bulk hydrogen. Moreover, we use our PIMC results as a reference to rigorously assess the accuracy of a variety of exchange−correlation (XC) functionals in density functional theory calculations for different density regions. Here, a key finding is the importance of thermal XC effects for the accurate description of density gradients in high-energy-density systems. Our exact PIMC test set is freely available online and can be used to guide the development of new methodologies for the simulation of warm dense matter and beyond.

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Section: Discussionmentioning

confidence: 82%

Section: Resultsmentioning

confidence: 99%

Bound-State Breaking and the Importance of Thermal Exchange–Correlation Effects in Warm Dense Hydrogen

Moldabekov,

Schwalbe,

Böhme

et al. 2023

J. Chem. Theory Comput.

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“…From a physical perspective, one can expect that such measurements will be highly sensitive to the density of the probed system and, in this way, will complement backward scattering measurements that are particularly sensitive to parameters such as the temperature and ionization. 101 − 103 In accordance with this reasoning, a second potential application of the ξ extrapolation method that is related to the study of WDM concerns the estimation of thermodynamic quantities and transport coefficients such as thermal conductivity 60 and electrical conductivity, 59 which may substantially depend on exchange–correlation effects. 54 …”

mentioning

confidence: 98%

“…More importantly, the ξ extrapolation method will allow for the first time the study of long-range phenomena in real WDM systems based on ab initio PIMC simulations starting with hydrogen. − This will facilitate the interpretation of XRTS experiments in a forward scattering geometry, where the system is effectively probed on large length scales. From a physical perspective, one can expect that such measurements will be highly sensitive to the density of the probed system and, in this way, will complement backward scattering measurements that are particularly sensitive to parameters such as the temperature and ionization. − In accordance with this reasoning, a second potential application of the ξ extrapolation method that is related to the study of WDM concerns the estimation of thermodynamic quantities and transport coefficients such as thermal conductivity and electrical conductivity, which may substantially depend on exchange–correlation effects …”

mentioning

confidence: 98%

Ab Initio Path Integral Monte Carlo Simulations of the Uniform Electron Gas on Large Length Scales

Dornheim,

Schwalbe,

Moldabekov

et al. 2024

J. Phys. Chem. Lett.

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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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“…Electron delocalization significantly influences the physical properties of condensed materials, both in astrophysical objects and on Earth. K-shell electron delocalization, observed under pressures exceeding billions of atmospheres, has a substantial impact on factors such as the equation of state, radiation transport, and the structure and evolution of astrophysical objects . High-shell electron delocalization is commonly observed in metals, conferring exceptional properties such as electronic conductivity of silver, thermal conductivity of copper, and ferromagnetism of iron.…”

mentioning

confidence: 99%

Nonbonding Electron Delocalization Stabilizes the Flexible N₈ Molecular Assembly

Yao,

Dou,

Yang

et al. 2024

J. Phys. Chem. Lett.

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Electron delocalization has an important impact on the physical properties of condensed materials. However, the L-electron delocalization in inorganic, especially nitrogen, compounds needs exploitation to improve the energy efficiency, safety, and environmental sustainability of high-energy-density materials (HEDMs). This Letter presents an intriguing N 8 molecule, ingeniously utilizing nitrogen's L-electron delocalization. The molecule, exhibiting a unique lollipop-shaped conformation, can fold at various angles with very low energy barriers, self-assembling into environmentally stable, all-nitrogen crystals. These crystals demonstrate unparalleled stability, high energy density, low mechanical sensitivity, and optimal electronic thermal conductivity, outperforming existing HEDMs. The remarkable properties of these designed materials are attributed to two distinct delocalized systems within nitrogen's L-shell: πand lone pair σ-electrons, which not only stabilize the molecular structure but also facilitate interconnected 3D networks of intermolecular nonbonding interactions. This work might pave the way to the experimental synthesis of environmentally stable all-nitrogen solids.

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Observing the onset of pressure-driven K-shell delocalization

Cited by 30 publications

References 51 publications

Bound-State Breaking and the Importance of Thermal Exchange–Correlation Effects in Warm Dense Hydrogen

Bound-State Breaking and the Importance of Thermal Exchange–Correlation Effects in Warm Dense Hydrogen

Ab Initio Path Integral Monte Carlo Simulations of the Uniform Electron Gas on Large Length Scales

Nonbonding Electron Delocalization Stabilizes the Flexible N₈ Molecular Assembly

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Observing the onset of pressure-driven K-shell delocalization

Cited by 30 publications

References 51 publications

Bound-State Breaking and the Importance of Thermal Exchange–Correlation Effects in Warm Dense Hydrogen

Bound-State Breaking and the Importance of Thermal Exchange–Correlation Effects in Warm Dense Hydrogen

Ab Initio Path Integral Monte Carlo Simulations of the Uniform Electron Gas on Large Length Scales

Nonbonding Electron Delocalization Stabilizes the Flexible N8 Molecular Assembly

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Product

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Nonbonding Electron Delocalization Stabilizes the Flexible N₈ Molecular Assembly