Computational Investigations of Dispersion Interactions between Small Molecules and Graphene-like Flakes

We investigate dispersion interactions
in a selection of atomic,
molecular, and molecule–surface systems, comparing high-level
correlated methods with empirically corrected density functional theory
(DFT). We assess the efficacy of functionals commonly used for surface-based
calculations, with and without the D3 correction of Grimme. We find
that the inclusion of the correction is essential to get meaningful
results, but there is otherwise little to distinguish between the
functionals. We also present coupled-cluster quality interaction curves
for H2, NO2, H2O, and Ar interacting
with large carbon flakes, acting as models for graphene surfaces,
using novel absolutely localized molecular orbital based methods.
These calculations demonstrate that the problems with empirically
corrected DFT when investigating dispersion appear to compound as
the system size increases, with important implications for future
computational studies of molecule–surface interactions.