Gold and platinum microclusters and their anions: comparison of structuraland electronic properties

We present a study of Au-2 to Au-5 and Pt-2 to Pt-5 clusters within density -functional theory in the neutral and anionic states. Results obtained usin g two exchange-correlation (xc) functionals, local spin density approximati on and spin-polarized Becke-Lee-Yang-Parr (BLYP), are compared. The structu ral characteristics and relative stabilities of different isomers as well a s electron affinities and vertical detachment energies are calculated. The latter compare generally well with experimental data, especially in the BLY P case. However, strong dependence of the vertical electron detachment ener gies on the isomer and on the re-functional scheme indicates that special c are must be taken for any comparison of theoretical results with experiment . Both for platinum and gold tetramers and pentamers, 3D geometries are unf avored. Triplet states are predicted to be more stable than singlets for pl atinum, for all sizes considered. The relative stability of different geome trical isomers is strongly affected by the addition of one electron. Marked differences emerge in the electronic structure between the clusters of the se two metals. (C) 2000 Elsevier Science B.V. All rights reserved.