Although noncovalent interactions are orders of magnitude weaker than covalent bonds, they critically affect many physical properties of chemical systems. They shape the structures of molecular crystals, influence the bulk properties of gases, affect the spectroscopy of molecular complexes, and alter chemical reactions. Beyond phenomena related to changes in the potential energy of weakly bound systems, these interactions can also lead to electron density deformations, causing electron flow between different parts of the interacting systems. Properties sensitive to these changes in electron density deserve special attention. For example, modifications to dipole moments induced by interactions, which determine collision-induced absorption coefficients depend, apart from potential energy surfaces, on dipole moment surfaces. Similarly, NMR spectroscopy parameters in crystals, such as shielding constants and chemical shifts, are affected by these interactions. In addition, induced dipole moments and polarizabilities influence the dielectric properties of gases and their mixtures. More recently, scattering Feshbach resonances in the ultralow kinetic energy regime turned out to be driven by the modification of the hyperfine atomic coupling in collisions of alkali metal atoms with closed shell species. Among many approaches, symmetry-adapted perturbation theory (SAPT) has proven to be one of the best tools for studying noncovalent interactions. The current range of applicability of SAPT spans small to large systems with 100-200 atoms . In addition, the range of possible systems includes open-shell and multiconfigurational systems or even autoionizing dimers. The central concept of the SAPT methods is the partitioning of the dimer Hamiltonian into the Hamiltonians of the monomers and the interaction operator between the subsystems