Examining the error statistics for the Karlsruhe basis sets in Table , it appears that absolute errors converge at the triple-ζ level. Difference between triple-and quadruple-ζ interaction energies are uniformly smaller than 1 kcal/mol and on average these differences are no more than 0.2-0.3 kcal/mol. The largest differences (approaching 1 kcal/mol) are for systems with very strong hydrogen bonds, such as acetic acid dimer, and in those cases the quadruple-ζ errors are actually larger than the triple-ζ errors, albeit by a very small amount.