Dynamical screening of van der Waals interaction between graphene layers

Abstract

The interaction between graphene layers is analyzed combining local orbital DFT and second order perturbation theory. For this purpose we use the Linear Combination of Atomic Orbitals -Orbital Occupancy (LCAO-OO) formalism, that allows us to separate the interaction energy as a sum of a weak chemical interaction between graphene layers plus the van der Waals interaction [1]. In this work, the weak chemical interaction is calculated by means of corrected-LDA calculations using an atomic-like sp3d5 basis set. The van der Waals interaction is calculated by means of second order perturbation theory using an atom-atom interaction approximation and the atomiclike orbital occupancies. We also analyze the effect of dynamical screening in the van der Waals interaction using a simple model. We find that this dynamical screening reduces the van der Waals energy between graphene layers by 22 meV/atom , which represents a 40% reduction in the van der Waals interaction. Taking into account this dynamical screening, we obtain a graphene-graphene interaction of 64 meV/atom, in good agreement with the experimental evidence. 2