Interpretation of van der Waals density functionals

TL;DR

This paper interprets the nonlocal correlation energy in van der Waals density functionals as a coupling of zero-point energies of characteristic modes of exchange-correlation holes, providing insights into the nonlocality of the method.

Contribution

It offers a new interpretation of the nonlocal correlation energy in vdW-DF in terms of xc hole modes, linking it to GGA properties and clarifying the nonlocal correlation formulation.

Findings

xc holes share properties with GGA

illustrates nonlocality in vdW-DF

analyzes the formulation of nonlocal correlation

Abstract

The nonlocal correlation energy in the van der Waals density functional (vdW-DF) method [Phys. Rev. Lett. 92, 246401 (2004); Phys. Rev. B 76, 125112 (2007); Phys. Rev. B 89, 035412 (2014)] can be interpreted in terms of a coupling of zero-point energies of characteristic modes of semilocal exchange-correlation (xc) holes. These xc holes reflect the internal functional in the framework of the vdW-DF method [Phys. Rev. B 82, 081101(2010)]. We explore the internal xc hole components, showing that they share properties with those of the generalized-gradient approximation. We use these results to illustrate the nonlocality in the vdW-DF description and analyze the vdW-DF formulation of nonlocal correlation.