Molecular polarisabilities - a comparison of density functional theory with standard ab initio methods

Molecular polarisabilities calculated with density functional theory using both the local density approximation and a gradient corrected functional are contrasted with results obtained using standard ab initio methods. The ab initio methods used are SCF, second-order and fourth-order Mّller-Plesset perturbation theory and coupled-cluster methods using Brueckner orbitals. The best agreement with experimental data comes from the coupled-cluster calculations. SCF values are systematically too low, and DFT results are too high.