Noncovalent intermolecular interactions play a pivotal role in many physical, chemical, and biological phenomena. They are vital for the formation of molecular crystals, dictate the interactions between organic compounds and inorganic surfaces, and are instrumental in numerous biological processes, such as biomolecule folding, to name just a few. The exchange interactions are the main constituent of the repulsive forces of van der Waals interactions. At relatively small intermolecular separations, the electron densities of two molecules begin to overlap, causing the electrons to rearrange in a way that avoids violating the Pauli exclusion principle. This interaction results in a short-range repulsive force that prevents atoms and molecules from coming into close contact and was first discussed already in 1930 by Eisenschitz and London. The exchange forces can only be accurately reproduced within perturbation theory by ensuring the correct permutational symmetry of the perturbation expansion. In the Symmetry-Adapted Perturbation Theory (SAPT), the dimer's Hamiltonian is partitioned into the unperturbed one (the sum of individual Hamiltonians of isolated monomers ĤA + ĤB ) and the interaction between monomers ( V ) so that Ĥ = ĤA + ĤB + V .