Carbohydrate-aromatic pi interactions: a test of density functionals and the DFT-D method

The performance of a number of computational approaches based upon density functional theory (DFT) for the accurate description of carbohydrate-pi interactions is described. A database containing interaction energies of a small number of representative complexes, computed at a high ab initio level, is described, and is used to judge 18 different density functionals including the M05 and M06 families as well as the DFT method augmented with empirical dispersive corrections (DFT-D). The DFT-D method and the M06 functionals are found to perform particularly well, whilst traditional functionals such as B3LYP perform poorly. The interaction energies for 23 sugar-aromatic complexes calculated by the DFT-D method are compared with the values from the 18 functionals. Again, the M06 class of functional is found to be superior.