Systematic testing of Gaussian and complete basis set methods with dispersion corrections for environmentally relevant clusters

Results are presented demonstrating the ability of CBS-x and Gn theory to predict energies for non-covalently bound complexes, both uncorrected and upon implementation of dispersion-sensitive DFT. CBS-QCI/APNO performs best among uncorrected methods (MUE 0.88 kcal mol−1), while G4 (MUE 1.05 kcal mol−1) and CBS-QB3 (MUE 1.13 kcal mol−1) provide energies close to that of CBS-QCI/APNO, but at a reduced cost. Inclusion of B2PLYP-D and B97-D as well as M0N-2X type functionals into G4 and CBS-QB3 results in improved binding energies. From a comparison with CCSD(T)/CBS results, M05-2X/CBS-QB3 structures and binding energies provide a cost-effective and accurate description of environmentally relevant non-covalent interactions.