For the S66 dimes, CP-DFT in small basis sets can be used to obtain interaction energies that are within ∼ 0.2 kcal/mol of the DFT/CBS limit for the same functional, a convergence error that is smaller than the intrinsic accuracy of the bests contemporary functionals for these same complexes. For coronene dimer, however, the CP correction is larger in double-ζ basis sets. In this section, we examine much larger molecular systems in order to understand how the magnitude of BSSE grows with system size. Systems examined include a set of layered complexes of oligothiophenes and graphene nanoribbons, such as the example shown in Fig. . These range in size from 134-174 atoms and have ∆E int in the range 60-100 kcal/mol, depending on functional and basis set. We also examine four protein-ligand systems ranging from 261-323 atoms, whose DFT/CBS interaction energies range from 15-100 kcal/mol; two of these are shown in Fig. and. As in the calculations reported above, our primary goal is not to evaluate ∆E int against some benchmark value but rather to examine convergence to the DFT/CBS limit and to assess the efficacy of CP correction in obtaining that limit. sis set. For the S66 dimers, the latter basis affords absolute convergence errors smaller than 0.15 kcal/mol for the two functionals considered here, and CP-DFT/def2-TZVPD affords interaction energies comparable to DFT/ def2-QZVPD for the S66 dimers.