are already lower than the CBS PW values). For this smaller test set, Feller occasionally beats Peterson, but Helgaker and Martin4 perform consistently better, too. Therefore, if the extrapolation sequence includes the D zeta level, it is suggested to use the Helgaker (28)(29) scheme on aug-cc-pVXZ CPcorrected energies in order to obtain the most accurate estimates in the CBS limit. If not, the Martin4 (23) expression is recommended.