Towards accurate orbital-free simulations: A generalized gradient approximation for the noninteracting free energy density functional

Luo, Kai; Karasiev, Valentin V.; Trickey, S. B.

doi:10.1103/physrevb.101.075116

Cited by 34 publications

(19 citation statements)

References 41 publications

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“…We have calculated the CHON EOS at 10 5 K or higher temperatures by employing an orbital-free (OF) DFT MD approach with the Luo-Karasiev-Trickey γ Thomas-Fermi (LKTγ TF) tunable noninteracting free-energy functionals [34]. The thermal functional is constructed through a convex combination of LKT GGA [35] and TF [36] functionals:…”

Section: B Kohn-sham Dft MD For Low-temperature Calculationsmentioning

confidence: 99%

First-principles equation of state of CHON resin for inertial confinement fusion applications

Zhang

Karasiev²,

Shaffer³

et al. 2022

Phys. Rev. E

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A wide-range (0 to 1044.0 g/cm 3 and 0 to 10 9 K) equation-of-state (EOS) table for a CH 1.72 O 0.37 N 0.086 quaternary compound has been constructed based on density-functional theory (DFT) molecular-dynamics (MD) calculations using a combination of Kohn-Sham DFT MD, orbital-free DFT MD, and numerical extrapolation. The rst-principles EOS data are compared with predictions of simple models, including the fully ionized ideal gas and the Fermi-degenerate electron gas models, to chart their temperature-density conditions of applicability. The shock Hugoniot, thermodynamic properties, and bulk sound velocities are predicted based on the EOS table and compared to those of C-H compounds. The Hugoniot results show the maximum compression ratio of the C-H-O-N resin is larger than that of CH polystyrene due to the existence of oxygen and nitrogen; while the other properties are similar between CHON and CH. Radiation hydrodynamic simulations have been performed using the table for inertial connement fusion targets with a CHON ablator and compared with a similar design with CH. The simulations show CHON outperforms CH as the ablator for laser-direct-drive target designs.

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Section: B Kohn-sham Dft MD For Low-temperature Calculationsmentioning

confidence: 99%

First-principles equation of state of CHON resin for inertial confinement fusion applications

Zhang

Karasiev²,

Shaffer³

et al. 2022

Phys. Rev. E

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“…14 for a wide range of temperatures T = 250 − 400000 K. For completeness, we mention that simulations of temperature ranges be-yond 400000 K are at present computationally too expensive using KS-DFT. Alternatives include orbital-free DFT [80][81][82][83] and an extended KS-formalism 82 , which, however, are beyond the scope of this work. We have performed simulations for a system size N = 256 and the k -point sampling is performed only at the Γpoint.…”

Section: Computational Detailsmentioning

confidence: 99%

Influence of finite temperature exchange-correlation effects in hydrogen

2020

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We use density functional molecular dynamics (DFT-MD) to study the effect of finite temperature exchange-correlation (xc) in Hydrogen. Using the Kohn-Sham approach, the xc energy of the system, Exc(rs) is replaced by the xc free energy fxc(rs, Θ) within the local density approximation (LDA) based on parametrized path integral Monte Carlo (PIMC) data for the uniform electron gas (UEG) at warm dense matter (WDM) conditions. We observe insignificant changes in the equation of state (EOS) at the region of metal-insulator transition compared to the regular LDA form, whereas significant changes are observed for T>10000 K, i.e., in the important WDM regime. Thus, our results further corroborate the need for temperature-dependent xc functionals for DFT simulations of WDM systems. Moreover, we present the first finite-temperature DFT results for the EOS of Hydrogen in the electron liquid regime up to rs = 14 and find a drastic impact (the EOS changes by more than 20%) of thermal xc effects, which manifests at lower temperatures compared to WDM. We expect our results to be important for many applications beyond DFT, like quantum hydrodynamics and astrophysical models.

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“…At higher temperatures, a large number of one-body states is occupied with non-negligible probabilities. Orbital-free density functional theories (ofDFT) aim at mitigating this with functionals that do not depend on the usual Kohn–Sham orbital description of DFT. , Canonical or grand-canonical full configuration interaction methods can be used for benchmarking more approximate theories . Finally, various forms of Monte Carlo methods approach the finite-temperature many-body problem in complementary ways as they exhibit entirely different error sources.…”

Section: Introductionmentioning

confidence: 99%

On the Chemical Potential of Many-Body Perturbation Theory in Extended Systems

Hummel

2023

J. Chem. Theory Comput.

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Finite-temperature many-body perturbation theory in the grand-canonical ensemble is fundamental to numerous methods for computing electronic properties at nonzero temperature, such as finitetemperature coupled-cluster. In most applications it is the average number of electrons that is known rather than the chemical potential. Expensive correlation calculations must be repeated iteratively in search for the interacting chemical potential that yields the desired average number of electrons. In extended systems with mobile charges the situation is particular, however. Long-ranged electrostatic forces drive the charges such that the average ratio of negative and positive charges is one for any finite chemical potential. All properties per electron are expected to be virtually independent of the chemical potential, as they are in an electric wire at different voltage potentials. This work shows that per electron, the exchange-correlation free energy and the exchange-correlation grand potential indeed agree in the infinite-size limit. Thus, only one expensive correlation calculation suffices for each system size, sparing the search for the interacting chemical potential. This work also demonstrates the importance of regularizing the Coulomb interaction such that each electron on average interacts only with as many electrons as there are electrons in the simulation, avoiding interactions with periodic images. Numerical calculations of the warm uniform electron gas have been conducted with the Spencer−Alavi regularization employing the finite-temperature Hartree approximation for the self-consistent field and linearized finite-temperature direct-ring coupled-cluster doubles for treating correlation.

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Towards accurate orbital-free simulations: A generalized gradient approximation for the noninteracting free energy density functional

Cited by 34 publications

References 41 publications

First-principles equation of state of CHON resin for inertial confinement fusion applications

First-principles equation of state of CHON resin for inertial confinement fusion applications

Influence of finite temperature exchange-correlation effects in hydrogen

On the Chemical Potential of Many-Body Perturbation Theory in Extended Systems

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