Finally, in an effort to gauge the absolute accuracy of these ligand-protein interaction energies, we take advantage of a recent CCSD(T)/CBS benchmark for the 1HSG:indinavir system. 107 Table shows how ωB97M-V performs against this benchmark using various basis sets. CP-corrected values of ∆E int lie within 10 kcal/mol of the benchmark (representing 8% error), even for basis sets as small as def2-SVP. This is certainly a much Connected points illustrate convergence of ∆Eint in Karlsruhe basis sets, both with and without CP correction. For comparison, values of ∆Eint in the 6-31+G* basis set are also shown. The ωB97M-V/CBS limit, obtained by averaging def2-ma-QZVP interaction energies with and without CP correction, is indicated by the horizontal line and its numerical value is also indicated. larger absolute error as compared to those obtained for S66 dimers, but the percentage errors are typically 7-8% when CP correction is used, although the ωB97M-V/def2-SVP value is slightly more accurate. Errors increase substantially in the absence of CP correction, up to 54 kcal/mol (45% error) in the smallest basis set tested.