All calculations were carried out with a development version of the ORCA program package based on version 5.0. In DLPNO-CCSD(T) calculations of water clusters, -TightPNO‖ settings were used and triples contributions were computed by using the iterative (T 1 ) algorithm. The augcc-pVTZ and aug-cc-pVQZ basis sets were used. The results were extrapolated to the complete basis set limit, i.e., CBS(3/4), and to the complete PNO space limit, i.e., CPS(6/7). In the DLPNO-CCSD(T) calculations of the nAChR protein, NormalPNO* settings were used and triples contribution was computed by using semi-canonical (T 0 ) algorithm. The def2-TZVPP and its matching auxiliary basis sets were used. HFLD calculations on the DIAD-COT crystal and DNA duplex were performed with the NormalPNO* settings. The def2-TZVP(-f) and its matching auxiliary basis sets were used. The water environment in the DNA system was treated implicitly by using the Conductor-like Polarizable Continuum Model (CPCM) within the perturbation theory and energy (PTE) approach.