Performance of the 'parameter free' PBE0 functional for the modeling of molecular properties of heavy metals

A comparative density functional study of a new functional (PBE) and of the corresponding hybrid version (PBE0) has been performed on LnX(3) species ( X = F, Cl, Br, I and Ln = La, Gd, Lu), including a relativistic effective c ore potential. Geometry optitnizations and harmonic frequency calculations were carried out. Both PBE and PBE0 give better results than previous B3LYP computations, and the hybrid PBE0 was found to perform better than the PBE functional for the reproduction of geometrical features, while both give s imilar good agreement for frequencies. Finally, the addition of polarizatio n functions in the halogen basis set greatly improves both geometric parame ters and frequencies. (C) 2000 Elsevier Science B.V. All rights reserved.