Pii: S0166-1280(00)00812-5

The static mean polarisabilities a and polarisability anisotropies Da of nine molecules have been computed at the B3LYP level by using 6-31111G(3df,2pd), aug-cc-pVDZ and Sadlej basis sets, experimental re or optimised geometries. These molecules are either linear (CO2, CS2, OCS, HCCH) or symmetric top (CH3CCH, CH3Cl, CHCl3, CH3CN, C6H6). A statistical comparison with accurate experimental data has shown that 6-31111G(3df,2pd) basis set gives slightly better results than the two other sets. More precisely, for a…0†; Sadlej basis set has the best statistical indicators to experiment, but a 0.98 scale factor should be applied to calculated values to improve agreement with experimental values, wherefore no scale factor is needed with 6-31111G(3df,2pd) basis set. For Da (0), B3LYP/6-31111G(3df,2pd) method clearly performs the best results, however, a 0.96 scale factor is necessary to ®t experiment. Also, computed polarisabilities are better when the experimental microwave geometry is used instead of the geometry computed by optimisation. q 2001 Elsevier Science B.V. All rights reserved.