Improved ground-state electronic structure and optical dielectric constants with a semilocal exchange functional

Vlček, Vojtěch; Steinle‐Neumann, Gerd; Leppert, Linn; Armiento, Rickard; Kümmel, Stephan

doi:10.1103/physrevb.91.035107

Cited by 22 publications

(24 citation statements)

References 105 publications

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“…Thus, both realigned versions of the AK13 and the BJ potential mimic a feature associated with the derivative discontinuity (DD) [16] of the exact exchange (EXX) functional. Moreover, both models for exchange share additional attractive properties such as a step structure in the potential for well-separated subsystems and an improved shell structure in the potential for atoms [36,55]; in bulk systems, they show band gaps, band structures, and optical dielectric constants closer to EXX results [50,55,60]and are thus typically in better agreement with experiments. Hence, AK13 and BJ functionals implement several promising features.…”

Section: Ak13 and Bj Model Reviewmentioning

confidence: 90%

Challenges for semilocal density functionals with asymptotically nonvanishing potentials

2017

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have been shown to mimic features of the exact Kohn-Sham exchange potential, such as step structures that are associated with shell closings and particle-number changes. A key element in the construction of these functionals is that the potential has a limiting value far outside a finite system that is a system-dependent constant rather than zero. We discuss a set of anomalous features in these functionals that are closely connected to the nonvanishing asymptotic potential. The findings constitute a formidable challenge for the future development of semilocal functionals based on the concept of a nonvanishing asymptotic constant.

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Section: Ak13 and Bj Model Reviewmentioning

confidence: 90%

Challenges for semilocal density functionals with asymptotically nonvanishing potentials

2017

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“…28,36,66,67 In addition to these potentials, we consider in this work the BJ potential 22 which is of stray type (see Refs. 32 and 37) and has the form…”

Section: Talman and Shadwickmentioning

confidence: 99%

Comparison between exact and semilocal exchange potentials: An all-electron study for solids

et al. 2015

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The exact-exchange (EXX) potential, which is obtained by solving the optimized-effective potential (OEP) equation, is compared to various approximate semilocal exchange potentials for a set of selected solids (C, Si, BN, MgO, Cu2O, and NiO). This is done in the framework of the linearized augmented plane-wave method, which allows for a very accurate all-electron solution of electronic structure problems in solids. In order to assess the ability of the semilocal potentials to approximate the EXX-OEP, we considered the EXX total energy, electronic structure, electric-field gradient, and magnetic moment. An attempt to parameterize a semilocal exchange potential is also reported.

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“…Experimental values of the fundamental gaps are from Refs. [11,29]. We emphasize that one cannot make a direct quantitative comparison between KS band gaps and experimental gaps.…”

Section: Results On Atomic Energies and The Energetics Of Solidsmentioning

confidence: 96%

“…Compared to the local-density approximation (LDA), and the widely used generalized-gradient approximation (GGA) functional of Perdew, Burke, and Ernzerhof [10] (PBE), it improves on the electronic structure and optical dielectric constants [11], which indicates that its KS orbitals resemble more the true quasiparticle electron states of the system. For atoms and small molecules, Cerceira et al found an overall improvement of the first ionization potential as obtained from the highest occupied KS eigenvalue [12].…”

Section: Introductionmentioning

confidence: 99%

Energetics of the AK13 semilocal Kohn-Sham exchange energy functional

Lindmaa

Armiento

2016

Phys. Rev. B

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The recent nonempirical semilocal exchange functional of Armiento and Kümmel [Phys. Rev. Lett. 111, 036402 (2013)], AK13, incorporates a number of features reproduced by higher-order theory. The AK13 potential behaves analogously with the discontinuous jump associated with the derivative discontinuity at integer particle numbers. Recent works have established that AK13 gives a qualitatively improved orbital description compared to other semilocal methods, and reproduces a band structure closer to higher-order theory. However, its energies and energetics are inaccurate. The present work further investigates the deficiency in energetics. In addition to AK13 results, we find that applying the local-density approximation (LDA) non-self-consistently on the converged AK13 density gives very reasonable energetics with equilibrium lattice constants and bulk moduli well described across 13 systems. We also confirm that the attractive orbital features of AK13 are retained even after full structural relaxation. Hence, the deficient energetics cannot be a result of the AK13 orbitals having adversely affected the quality of the electron density compared to that of usual semilocal functionals; an improved orbital description and good energetics are not in opposition. This is also confirmed by direct calculation of the principal component of the electric field gradient. In addition, we prove that the non-self-consistent scheme is equivalent to using a single external-potential-dependent functional in an otherwise consistent, nonvariational Kohn-Sham density-functional theory (KS DFT) scheme. Furthermore, our results also demonstrate that, while an internally consistent KS functional is presently missing, non-self-consistent LDA on AK13 orbitals works as a practical nonempirical computational scheme to predict geometries, bulk moduli, while retaining the band structure features of AK13 at the computational cost of semi-local DFT.

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Improved ground-state electronic structure and optical dielectric constants with a semilocal exchange functional

Cited by 22 publications

References 105 publications

Challenges for semilocal density functionals with asymptotically nonvanishing potentials

Challenges for semilocal density functionals with asymptotically nonvanishing potentials

Comparison between exact and semilocal exchange potentials: An all-electron study for solids

Energetics of the AK13 semilocal Kohn-Sham exchange energy functional

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