Nonlocal van der Waals Density Functional Made Simple

We derive a nonlocal correlation functional that adequately describes van der Waals interactions not only in the asymptotic long-range regime but also at short range. Unlike its precursor, developed by Langreth, Lundqvist, and co-workers, the new functional has a simple analytic form, finite for all interelectron separations, well behaved in the slowly varying density limit, and generalized to spin-polarized systems.

Figure 1

The integrand of Eq. (16): $4\pi D(K)/K^4$.

Figure 2

LCS-VV09 binding energy curves for two diatomics, computed with the aug-cc-pVQZ basis set and $(99,302)$ grid. Experimental potential energy minimum for ${\mathrm{Ar}}_2$ (+ symbol) is from Ref. 26 and for Kr-Cl (× symbol) from Ref. 27.