The calculation of the dispersion energy is a daunting task for two main reasons: it is very sensitive to intramonomer correlation effects and secondly, it is slowly convergent with respect to the basis set size. These properties of the dispersion energy make the calculation of the van der Waals interactions difficult: in particular this is one of the main reasons why the supermolecular calculations of interaction energies are also challenging -the methods used need to include the high-order electronic correlation effects, the basis sets employed need to be highly saturated and include augmented functions, or explicit correlation. Notably, for many-body electron methods, triply excited configurations are often critical to properly describe the dispersion interaction, which lead to emergence of CCSD(T) method as the "gold standard" in calculations of the interaction energies in non-covalent systems.