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Thelen TQ, Rehn DA, Fontes CJ, Starrett CE. Predicting excitation energies in warm and hot dense matter. Phys Rev E 2024; 110:015207. [PMID: 39161004 DOI: 10.1103/physreve.110.015207] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2024] [Accepted: 07/10/2024] [Indexed: 08/21/2024]
Abstract
In a dense plasma environment, the energy levels of an ion shift relative to the isolated ion values. This shift is reflected in the optical spectrum of the plasma and can be measured in, for example, emission experiments. In this work we use a recently developed method of modeling electronic states in warm dense matter to predict these level energies. In this model excited state energies are calculated directly by enforcing constrained one-electron occupation factors, thus allowing the calculation of specific transition and ionization energies. This model includes plasma effects self-consistently, so the effect of continuum lowering is included in an ab initio sense. We use the model to calculate the K-edge and K-alpha energies of solid density magnesium, aluminum, and silicon over a range of temperatures, finding close agreement with experimental results. We also calculate the ionization potential depression to compare to widely used models and investigate the effects of temperature on the lowering of the continuum.
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2
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Starrett CE, Thelen TQ, Fontes CJ, Rehn DA. Excited states in warm and hot dense matter. Phys Rev E 2024; 109:035201. [PMID: 38632718 DOI: 10.1103/physreve.109.035201] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2023] [Accepted: 02/06/2024] [Indexed: 04/19/2024]
Abstract
Accurate modeling of warm and hot dense matter is challenging in part due to the multitude of excited states that must be considered. Here, we present a variational framework that models these excited states. In this framework an excited state is defined by a set of effective one-electron occupation factors, and the corresponding energy is defined by the effective one-body energy with an exchange and correlation term. The variational framework is applied to an atom-in-plasma model (a generalization of the so-called average atom model). Comparisons with a density functional theory based average atom model generally reveal good agreement in the calculated pressure, but our model also gives access to the excitation energies and charge state distributions.
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Affiliation(s)
- C E Starrett
- Los Alamos National Laboratory, P.O. Box 1663, Los Alamos, New Mexico 87545, USA
| | - T Q Thelen
- Los Alamos National Laboratory, P.O. Box 1663, Los Alamos, New Mexico 87545, USA
| | - C J Fontes
- Los Alamos National Laboratory, P.O. Box 1663, Los Alamos, New Mexico 87545, USA
| | - D A Rehn
- Los Alamos National Laboratory, P.O. Box 1663, Los Alamos, New Mexico 87545, USA
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Cecconi V, Kumar V, Bertolotti J, Peters L, Cutrona A, Olivieri L, Pasquazi A, Totero Gongora JS, Peccianti M. Terahertz Spatiotemporal Wave Synthesis in Random Systems. ACS PHOTONICS 2024; 11:362-368. [PMID: 38405391 PMCID: PMC10885209 DOI: 10.1021/acsphotonics.3c01671] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/16/2023] [Revised: 12/28/2023] [Accepted: 12/29/2023] [Indexed: 02/27/2024]
Abstract
Complex media have emerged as a powerful and robust framework to control light-matter interactions designed for task-specific optical functionalities. Studies on wavefront shaping through disordered systems have demonstrated optical wave manipulation capabilities beyond conventional optics, including aberration-free and subwavelength focusing. However, achieving arbitrary and simultaneous control over the spatial and temporal features of light remains challenging. In particular, no practical solution exists for field-level arbitrary spatiotemporal control of wave packets. A new paradigm shift has emerged in the terahertz frequency domain, offering methods for absolute time-domain measurements of the scattered electric field, enabling direct field-based wave synthesis. In this work, we report the experimental demonstration of field-level control of single-cycle terahertz pulses on arbitrary spatial points through complex disordered media.
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Affiliation(s)
- Vittorio Cecconi
- Emergent
Photonics Research Centre, Department of Physics, School of Science, Loughborough University, Loughborough LE11 3TU, U.K.
- Emergent
Photonics Lab (EPic), Department of Physics and Astronomy, University of Sussex, Brighton BN1 9QH, U.K.
| | - Vivek Kumar
- Emergent
Photonics Lab (EPic), Department of Physics and Astronomy, University of Sussex, Brighton BN1 9QH, U.K.
| | - Jacopo Bertolotti
- Department
of Physics and Astronomy, University of
Exeter, Exeter, Devon EX4 4QL, U.K.
| | - Luke Peters
- Emergent
Photonics Research Centre, Department of Physics, School of Science, Loughborough University, Loughborough LE11 3TU, U.K.
- Emergent
Photonics Lab (EPic), Department of Physics and Astronomy, University of Sussex, Brighton BN1 9QH, U.K.
| | - Antonio Cutrona
- Emergent
Photonics Research Centre, Department of Physics, School of Science, Loughborough University, Loughborough LE11 3TU, U.K.
- Emergent
Photonics Lab (EPic), Department of Physics and Astronomy, University of Sussex, Brighton BN1 9QH, U.K.
| | - Luana Olivieri
- Emergent
Photonics Research Centre, Department of Physics, School of Science, Loughborough University, Loughborough LE11 3TU, U.K.
- Emergent
Photonics Lab (EPic), Department of Physics and Astronomy, University of Sussex, Brighton BN1 9QH, U.K.
| | - Alessia Pasquazi
- Emergent
Photonics Research Centre, Department of Physics, School of Science, Loughborough University, Loughborough LE11 3TU, U.K.
- Emergent
Photonics Lab (EPic), Department of Physics and Astronomy, University of Sussex, Brighton BN1 9QH, U.K.
| | - Juan Sebastian Totero Gongora
- Emergent
Photonics Research Centre, Department of Physics, School of Science, Loughborough University, Loughborough LE11 3TU, U.K.
- Emergent
Photonics Lab (EPic), Department of Physics and Astronomy, University of Sussex, Brighton BN1 9QH, U.K.
| | - Marco Peccianti
- Emergent
Photonics Research Centre, Department of Physics, School of Science, Loughborough University, Loughborough LE11 3TU, U.K.
- Emergent
Photonics Lab (EPic), Department of Physics and Astronomy, University of Sussex, Brighton BN1 9QH, U.K.
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Sadigh B, Åberg D, Pask J. Spectral-partitioned Kohn-Sham density functional theory. Phys Rev E 2023; 108:045204. [PMID: 37978681 DOI: 10.1103/physreve.108.045204] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2023] [Accepted: 09/13/2023] [Indexed: 11/19/2023]
Abstract
We introduce a general, variational scheme for systematic approximation of a given Kohn-Sham free-energy functional by partitioning the density matrix into distinct spectral domains, each of which may be spanned by an independent diagonal representation without requirement of mutual orthogonality. It is shown that by generalizing the entropic contribution to the free energy to allow for independent representations in each spectral domain, the free energy becomes an upper bound to the exact (unpartitioned) Kohn-Sham free energy, attaining this limit as the representations approach Kohn-Sham eigenfunctions. A numerical procedure is devised for calculation of the generalized entropy associated with spectral partitioning of the density matrix. The result is a powerful framework for Kohn-Sham calculations of systems whose occupied subspaces span multiple energy regimes. As a case in point, we apply the proposed framework to warm- and hot-dense matter described by finite-temperature density functional theory, where at high energies the density matrix is represented by that of the free-electron gas, while at low energies it is variationally optimized. We derive expressions for the spectral-partitioned Kohn-Sham Hamiltonian, atomic forces, and macroscopic stresses within the projector-augmented wave (PAW) and the norm-conserving pseudopotential methods. It is demonstrated that at high temperatures, spectral partitioning facilitates accurate calculations at dramatically reduced computational cost. Moreover, as temperature is increased, fewer exact Kohn-Sham states are required for a given accuracy, leading to further reductions in computational cost. Finally, it is shown that standard multiprojector expansions of electronic orbitals within atomic spheres in the PAW method lack sufficient completeness at high temperatures. Spectral partitioning provides a systematic solution for this fundamental problem.
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Affiliation(s)
- Babak Sadigh
- Lawrence Livermore National Laboratory, Livermore, California 94550, USA
| | - Daniel Åberg
- Lawrence Livermore National Laboratory, Livermore, California 94550, USA
| | - John Pask
- Lawrence Livermore National Laboratory, Livermore, California 94550, USA
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Shaffer NR, Starrett CE. Dense plasma opacity via the multiple-scattering method. Phys Rev E 2022; 105:015203. [PMID: 35193239 DOI: 10.1103/physreve.105.015203] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2021] [Accepted: 12/20/2021] [Indexed: 11/07/2022]
Abstract
The calculation of the optical properties of hot dense plasmas with a model that has self-consistent plasma physics is a grand challenge for high energy density science. Here we exploit a recently developed electronic structure model that uses multiple scattering theory to solve the Kohn-Sham density functional theory equations for dense plasmas. We calculate opacities in this regime, validate the method, and apply it to recent experimental measurements of opacity for Cr, Ni, and Fe. Good agreement is found in the quasicontinuum region for Cr and Ni, while the self-consistent plasma physics of the approach cannot explain the observed difference between models and the experiment for Fe.
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Affiliation(s)
- Nathaniel R Shaffer
- Los Alamos National Laboratory, P.O. Box 1663, Los Alamos, New Mexico 87545, USA and Laboratory for Laser Energetics, University of Rochester, 250 East River Road, Rochester, New York 14623, USA
| | - Charles E Starrett
- Los Alamos National Laboratory, P.O. Box 1663, Los Alamos, New Mexico 87545, USA
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Ottoway CF, Rehn DA, Saumon D, Starrett CE. Effect of ionic disorder on the principal shock Hugoniot. Phys Rev E 2021; 104:055208. [PMID: 34942703 DOI: 10.1103/physreve.104.055208] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2021] [Accepted: 11/11/2021] [Indexed: 11/07/2022]
Abstract
The effect of ionic disorder on the principal Hugoniot is investigated using multiple scattering theory to very high pressure (Gbar). Calculations using molecular dynamics to simulate ionic disorder are compared to those with a fixed crystal lattice, for both carbon and aluminum. For the range of conditions considered here we find that ionic disorder has a relatively minor influence. It is most important at the onset of shell ionization and we find that, at higher pressures, the subtle effect of the ionic environment is overwhelmed by the larger number of ionized electrons with higher thermal energies.
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Affiliation(s)
- Crystal F Ottoway
- Los Alamos National Laboratory, P.O. Box 1663, Los Alamos, New Mexico 87545, USA
| | - Daniel A Rehn
- Los Alamos National Laboratory, P.O. Box 1663, Los Alamos, New Mexico 87545, USA
| | - Didier Saumon
- Los Alamos National Laboratory, P.O. Box 1663, Los Alamos, New Mexico 87545, USA
| | - C E Starrett
- Los Alamos National Laboratory, P.O. Box 1663, Los Alamos, New Mexico 87545, USA
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Ovechkin AA, Loboda PA, Falkov AL, Sapozhnikov PA. Equation of state modeling with pseudoatom molecular dynamics. Phys Rev E 2021; 103:053206. [PMID: 34134221 DOI: 10.1103/physreve.103.053206] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2021] [Accepted: 04/28/2021] [Indexed: 11/07/2022]
Abstract
Using a modified version of the pseudoatom molecular-dynamics approach, the silicon and oxygen equations of state were generated and then employed to construct the equation of state of silicon dioxide. The results are supported by the close agreement with ab initio simulations of the silicon pressure and experimental shock Hugoniot of silicon dioxide. Ion thermal contributions to thermodynamic functions provided by the PAMD simulations are compared to their counterparts obtained with the one-component plasma and charged-hard-sphere approximations.
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Affiliation(s)
- A A Ovechkin
- Russian Federal Nuclear Center, Zababakhin All-Russian Research Institute of Technical Physics (RFNC-VNIITF), Snezhinsk, Chelyabinsk region 456770, Russia
| | - P A Loboda
- Russian Federal Nuclear Center, Zababakhin All-Russian Research Institute of Technical Physics (RFNC-VNIITF), Snezhinsk, Chelyabinsk region 456770, Russia.,National Research Nuclear University, Moscow Engineering Physics Institute (MEPhI), Moscow 115409, Russia
| | - A L Falkov
- Russian Federal Nuclear Center, Zababakhin All-Russian Research Institute of Technical Physics (RFNC-VNIITF), Snezhinsk, Chelyabinsk region 456770, Russia
| | - P A Sapozhnikov
- Russian Federal Nuclear Center, Zababakhin All-Russian Research Institute of Technical Physics (RFNC-VNIITF), Snezhinsk, Chelyabinsk region 456770, Russia
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