Accurate treatment of van der Waals interactions using standard density functional theory methods with effective core-type potentials: Application to carbon-containing dimers

Carbon atom-centered effective core-type potentials were developed to compensate for the incorrect long-range behaviour of density functionals and for limitations in basis set in treating van der Waals binding in dimers containing carbon atoms. Three method-specific potentials (PBE, PW91, B971) were designed. B971/6-311+G(2d,2p) was found to give binding energies for 22 dimers with mean absolute deviation from high-level results of 0.25 kcal/mol (13.0%). The potentials add little to calculation times and are useable with most computational chemistry programs. It is expected that such deficiencies in B86-based functionals can be largely corrected in the manner presented.