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 core 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 similar good agreement for frequencies. Finally, the addition of polarization functions in the halogen basis set greatly improves both geometric parameters and frequencies.