Pople versus Dunning basis-sets for group IA metal hydrides and some other second row hydrides: The case against a De Facto standard

This communication compares the ability of Dunning’s augmented correlation-consistent pVXZ (X = D, T, Q) basis sets to reproduce experimental spectroscopic bond lengths for a series of group IA metal hydrides M–H (M = H, Li, Na, K), as well as for BeH2, CH4, NH3, H2O and HF, with Pople’s 6-311++G(2d,p) triple split-valence basis set. Dunning’s aug-cc-pVDZ basis set in combination with MP2 or CCSD performed much less well than DFT methods in combination with 6-311++G(2d,p). MPW1PW91/6-311++G(2d,p) was found to give an accuracy only rivalled or bettered by the Dunning basis sets, pVTZ and pVQZ, at much reduced computational cost.