  We extend the method of Silvestrelli [P. L. Silvestrelli, J. Chem. Phys. 139,
054106 (2013)] to approximate long-range van der Waals interactions at the
density functional theory level based on maximally localized Wannier functions
combined with the quantum harmonic oscillator model, to periodic systems.
Applying this scheme to study London dispersion forces between graphene and
water layers, we demonstrate that collective many-body effects beyond simple
additive pair-wise interactions are essential to accurately describe van der
Waals forces.
