The results of an accurate density-functional study of the structure and energetics of Ptn clusters (with n = 13, 38, 55) are presented. For Pt38, a truncated octahedral geometry is considered; for Pt13 and Pt55, icosahedral, truncated decahedral and cuboctahedral geometries are considered. In each case, the structure of the neutral and positively and negatively charged clusters is fully optimized within the given symmetry group. For Pt13, allowing symmetry breaking starting from the symmetrical structures derives additional local minima. The computational procedure is thoroughly tested to keep numerical accuracy under control. It is found that these systems start developing metallic characteristics, with ionization introducing small changes. For Pt13, the icosahedral configuration is not favored, whereas it becomes the ground state for Pt55, in agreement with the predictions of atom-atom potentials. From the structural point of view, the lowest-energy configuration of Pt13 is a symmetry-broken D4h one, while for Pt38 and Pt55 a peculiar rearrangement is found, corresponding to an expansion (reconstruction) of the atoms lying on (111) or (100) faces.
Density functional calculations on platinum nanoclusters: Pt_13, Pt_38 and Pt_55
Fortunelli A
2003
Abstract
The results of an accurate density-functional study of the structure and energetics of Ptn clusters (with n = 13, 38, 55) are presented. For Pt38, a truncated octahedral geometry is considered; for Pt13 and Pt55, icosahedral, truncated decahedral and cuboctahedral geometries are considered. In each case, the structure of the neutral and positively and negatively charged clusters is fully optimized within the given symmetry group. For Pt13, allowing symmetry breaking starting from the symmetrical structures derives additional local minima. The computational procedure is thoroughly tested to keep numerical accuracy under control. It is found that these systems start developing metallic characteristics, with ionization introducing small changes. For Pt13, the icosahedral configuration is not favored, whereas it becomes the ground state for Pt55, in agreement with the predictions of atom-atom potentials. From the structural point of view, the lowest-energy configuration of Pt13 is a symmetry-broken D4h one, while for Pt38 and Pt55 a peculiar rearrangement is found, corresponding to an expansion (reconstruction) of the atoms lying on (111) or (100) faces.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
