Exchange functional that tests the robustness of the plasmon description of the van der Waals density functional

By Kristian Berland, Per Hyldgaard. 2013

445 citations recorded by the source corpus.

Is the plasmon description within the nonlocal correlation of the van der Waals density functional by Dion and coworkers (vdW-DF) robust enough to describe all exchange-correlation components? To address this question, we design an exchange functional based on this plasmon description as well as recent analysis on exchange in the large-s regime. In the regime with reduced gradients s = |del n|/2nk(F)(n) smaller than approximate to 2.5, dominating the nonlocal correlation part of the binding energy, the enhancement factor F-x(s) closely resembles the Langreth-Vosko screened exchange. In the s regime beyond, dominated by exchange, F-x(s) passes smoothly over to the revised Perdew-Wang-86 form. We term the specific exchange functional LV-PW86r, wheras the full van der Waals functional version emphasizing consistent handling of exchange is termed vdW-DF-cx. Our tests indicate that vdW-DF-cx produces accurate separations and binding energies of the S22 data set of molecular dimers as well as accurate lattice constants and bulk moduli of layered materials and tightly bound solids. These results suggest that the plasmon description within vdW-DF gives a good description of both exchange and correlation effects in the low-to-moderate s regime.

Subfields: Atomic and Molecular Physics, and Optics

View Paper: https://www.semanticscholar.org/paper/28f33b178dec9ee4dc82b27f7974c69de07ee55c

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In Atomic and Molecular Physics, and Optics

Citations in the corpus

Siesta: Recent developments and applications. (2020, methodology): “An efﬁcient calculation of van der Waals (vdW) functionals 35,36 was developed and ﬁrst implemented in S IESTA using a polynomial expansion in the local variables ( q 1 , q 2 ) of the nonlocal interaction kernel Φ ( q 1 , q 2 , r 12 ) and a Fourier expansion in the relative position r .”
van der Waals forces in density functional theory: a review of the vdW-DF method (2014, methodology): “This property ensures that the expression for the full xc energy (34) is charge conserving [59, 107, 109].”
Octopus, a computational framework for exploring light-driven phenomena and quantum dynamics in extended and finite systems. (2019, unknown): “Octopus supports the standard functionals vdW-DF1, 75,76 vdW-DF2, 77 and vdW-DF-cx, 78 as well as other common forms that differ by combining the correlation with a different exchange functional.”