Higher-accuracy van der Waals density functional

We propose a second version of the van der Waals density functional of Dion et al. [Phys. Rev. Lett. 92, 246401 (2004)], employing a more accurate semilocal exchange functional and the use of a large-$N$ asymptote gradient correction in determining the vdW kernel. The predicted binding energy, equilibrium separation, and potential-energy curve shape are close to those of accurate quantum chemical calculations on 22 duplexes. We anticipate the enabling of chemically accurate calculations in sparse materials of importance for condensed matter, surface, chemical, and biological physics.

This article appears in the following collection:

Figure 1

(Color online) PECs for the best and the worst case of (a) hydrogen-bonded, (b) dispersion-dominated, and (c) mixed duplexes. CCSD(T) QC PECs (dashed-dotted lines with circles taken from Ref. 33) and the reference energies (cross marks taken from Ref. 32) at the geometry of Ref. 31 are also shown. The shapes near minima are compared in inset figures where PECs are aligned to have the common minimum point. For all the other S22 duplexes, see supplementary material.

Figure 2

(Color online) Comparison for the S22 duplexes of (a) binding energy predicted by Jurecka et al. (Ref. 31), vdW-DF (Ref. 4), and the present work (vdW-DF2). (b) Binding energy at a separation $1\text{Å}$ larger than the equilibrium one and (c) equilibrium separations. The ordinates give the respective deviations of these quantities from the reference values taken from Takatani et al. (Ref. 32) for panel (a), Molnar et al. (Ref. 33) for panel (b), and Jurecka et al. (Ref. 31) for panel (c).