LAUSR

Applying a theoretical approach that combines an efficient and fast global optimization based on genetic algorithms (GA) to search in structure space and the parameterized density-functional tight-binding (DFTB) method for the calculation of the energy for a given structure, the structures of neutral and isolated Pt n clusters are determined with size n from 4 up to 60 atoms. For the analysis of the structural, energetic, and electronic properties of Pt n as a function of n , a series of descriptors are employed, including a stability function, the HOMO-LUMO energy gap, and atomic radial distances of the atoms, as well as a similarity function. The results demonstrate that the structural motifs change from planar to shell-like structures with low-symmetry. In addition, the growth patterns of Pt n clusters also are analyzed using these descriptors, suggesting that meta-stable isomers also play a role in the growth process. Studying the impact of zero-point vibration and of temperature on the energetic properties of the different isomers, we found only very small effects, implying that properties found for T = 0 are relevant also at elevated temperatures. On the other hand, even though Pt is the neighbor to Au in the periodic table, the properties of Pt n clusters differ markedly from those of Au n clusters, and it can therefore be expected that the properties of AuPt nanoalloys will not resemble those of the pure clusters.