(3.2.3) Fuentealba : Let me illustrate Schwerdtfeger's point regarding polarizabilities with some numbers. The dipole polarizability of a Li 4 cluster has been calculated using the B3LYP and PW91 functionals, the values being (in atomic units) 355 and 394, respectively . But the experimental value is 327 -no explanation. More dramatically, for the Cu 9 cluster, the calculated value is 295, while the experimental value is 984 278 . Pathetic.