A simple generalized gradient approximation for the noninteracting kinetic energy density functional

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

doi:10.1103/physrevb.98.041111

Cited by 91 publications

(92 citation statements)

References 49 publications

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“…Sec. IV], and as the basis for more sophisticated functionals such as a temperature-dependent generalized gradient approximation [127]. This opens up new avenues for DFT simulations of WDM systems without neglecting thermal effects in the XC-functional itself.…”

Section: A Summary Of Ab Initio Static Resultsmentioning

confidence: 99%

Ab initio simulation of warm dense matter

et al. 2020

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Warm dense matter (WDM) -an exotic state of highly compressed matter -has attracted high interest in recent years in astrophysics and for dense laboratory systems. At the same time, this state is extremely difficult to treat theoretically. This is due to the simultaneous appearance of quantum degeneracy, Coulomb correlations and thermal effects, as well as the overlap of plasma and condensed phases. Recent breakthroughs are due to the successful application of density functional theory (DFT) methods which, however, often lack the necessary accuracy and predictive capability for WDM applications. The situation has changed with the availability of the first ab initio data for the exchange-correlation free energy of the warm dense uniform electron gas (UEG) that were obtained by quantum Monte Carlo (QMC) simulations, for recent reviews, see Dornheim et al., Phys. Plasmas 24, 056303 (2017) and Phys. Rep. 744, 1-86 (2018). In the present article we review recent further progress in QMC simulations of the warm dense UEG: namely, ab initio results for the static local field correction G(q) and for the dynamic structure factor S(q, ω). These data are of key relevance for the comparison with x-ray scattering experiments at free electron laser facilities and for the improvement of theoretical models.In the second part of this paper we discuss simulations of WDM out of equilibrium. The theoretical approaches include Born-Oppenheimer molecular dynamics, quantum kinetic theory, timedependent DFT and hydrodynamics. Here we analyze strengths and limitations of these methods and argue that progress in WDM simulations will require a suitable combination of all methods. A particular role might be played by quantum hydrodynamics, and we concentrate on problems, recent progress, and possible improvements of this method.

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Section: A Summary Of Ab Initio Static Resultsmentioning

confidence: 99%

Ab initio simulation of warm dense matter

et al. 2020

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“…where the first term is the von Weizsäcker term T vW and the second term has two parameters C 2 and p, which need to be fixed. The RATIONAL p form unifies two previous kinetic energy functionals: Pauli-Gaussian [51] and LKT [50]. Any positive value of p yields a quite well performing kinetic functional.…”

Section: Generalized Gradient Approximationmentioning

confidence: 91%

“…The general trend seems to imply that while the non-local functionals do achieve better performance, improvements do come at the cost of specialization to a certain type of system [47,48,49]. Semilocal functionals do have a lower performance if we directly compare the best performing non-local functional and best performing semilocal on a chosen material but semilocal functionals are easily applied to any type of system (periodic, isolated) and have a competitive average performance [50,51]. However there are known limitations for performance on solids [52,53,54].…”

Section: Orbital-free Frameworkmentioning

confidence: 99%

Semilocal kinetic energy functionals with parameters from neutral atoms

Lehtomäki

Lopez-Acevedo

2019

Phys. Rev. B

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The author implemented the Englert-Schwinger model, collected the data, and analyzed the results. Manuscript was written jointly. Publication II: "Large-Z limit in atoms and solids from first principles" The author ran the DFT simulations, collected the data and analyzed the results. Manuscript was written jointly. Publication III: "Semilocal kinetic energy functionals with parameters from neutral atoms" The author implemented the kinetic energy functionals, collected the data and analyzed the results. Manuscript was written jointly. Publication IV: "Boron doping in gallium oxide from first principles" The author ran the DFT simulations, collected the data, and analyzed the results. Manuscript was written jointly.

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“…In that computational setting, VT84F (at T=0 K) can perform unreliably. Our response was to put forth the LKT ground-state functional 10 . It was formulated specifically to meet the rigorous positivity constraints in conjunction with ordinary pseudo-densities.…”

Section: B Adaptation To Pseudo-densitiesmentioning

confidence: 99%

“…With any significant ground-state advance, an obvious, important associated step is generalization to a non-interacting free energy functional F s . In this work, we make that step based upon a recently proposed ground state T s functional, LKT 10 . It has the novel property of being adapted specifically to working with pseudo-densities, such as almost always are used in AIMD calculations.…”

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confidence: 99%

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

2020

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For orbital-free ab initio molecular dynamics, especially on systems in extreme thermodynamic conditions, we provide the first pseudo-potential-adapted generalized gradient approximation (GGA) functional for the non-interacting free energy. This is achieved by systematic finite-temperature extension of our recent LKT ground state non-interacting kinetic energy GGA functional (Phys. Rev. B 98, 041111(R) (2018)). We test the performance of the new functional first via static lattice calculations on crystalline aluminum and silicon. Then we compare deuterium equation of state results against both path-integral Monte Carlo and conventional (orbital-dependent) Kohn-Sham results. The new functional, denoted LKTF, outperforms the previous best semi-local free energy functional, VT84F (Phys. Rev. B 88, 161108(R) (2013)), and provides modestly faster simulations. We also discuss subtleties of identification of kinetic and entropic contributions to non-interacting free-energy functionals obtained by extension from ground state orbital-free kinetic energy functionals.

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A simple generalized gradient approximation for the noninteracting kinetic energy density functional

Cited by 91 publications

References 49 publications

Ab initio simulation of warm dense matter

Ab initio simulation of warm dense matter

Semilocal kinetic energy functionals with parameters from neutral atoms

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

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