The accuracy of molecular dipole moments in standard electronic structure calculations

A systematic investigation has been carried out of the accuracy of calculat ed molecular equilibrium dipole moments of 11 polar closed-shell molecules, using the HF, MP2, CCSD and CCSD(T) models and correlation-consistent basi s sets. Augmented basis sets are important for improving the basis-set conv ergence, but the quality of the results depends more on the correlation tre atment than on the cardinal number of the basis set. Augmented triple-zeta basis sets are sufficient for most calculations. The mean absolute error of the HF calculations is 0.16 D, which is reduced at the MP2 and CCSD levels to 0.048 and 0.025 D, respectively. The CCSD(T) errors an small - typicall y < 0.01 D. (C) 2000 Elsevier Science B.V. All rights reserved.