Noncovalent Interactions in SIESTA Using the vdW-DF Functional: S22 Benchmark and Macrocyclic Structures.

We investigate the performance of the vdW-DF functional of Dion et al. implemented in the SIESTA code. In particular, the S22 data set and several calixarene-based host-guest structures are examined to assess the performance of the functional. The binding energy error statistics for the S22 data set reveal that the vdW-DF functional performs very well when compared to a range of other methods of treating dispersion in density functional theory, and to vdW-DF implementations in other codes. For the calixarene host-guest structures, the structural properties and binding energies are compared to previous experimental and computational studies, and in most cases we find that vdW-DF provides superior results to other computational studies.