Theoretical study of the structural and energetic properties of platinum clusters with up to 60 atoms
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ORIGINAL RESEARCH
Theoretical study of the structural and energetic properties of platinum clusters with up to 60 atoms Hao Xu1
· Mohammad Molayem1 · Michael Springborg1,2
Received: 28 September 2020 / Accepted: 11 November 2020 © Springer Science+Business Media, LLC, part of Springer Nature 2020
Abstract 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 Ptn clusters are determined with size n from 4 up to 60 atoms. For the analysis of the structural, energetic, and electronic properties of Ptn 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 Ptn 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 Ptn clusters differ markedly from those of Aun clusters, and it can therefore be expected that the properties of AuPt nanoalloys will not resemble those of the pure clusters. Keywords Platinum clusters · DFTB · Genetic algorithm · Structural and energetic properties
Introduction During the past several years, metal clusters have captured great interest from many scholars since their properties differ markedly from those of their corresponding bulk materials [1–3]. In addition, the properties depend strongly on cluster size [4, 5]. Since the structure and composition of a material dictate their properties, information on their structural modifications and growth patterns as a function of size is crucial for a deeper understanding of the materials properties [6, 7]. Among the different metals, platinum clusters is playing an important role because its unique properties make these systems useful for a wide range of applications such as catalysts for fuel cells, in jewelries, and
Hao Xu
[email protected] 1
Physical and Theoretical Chemistry, University of Saarland, 66123, Saarbr¨ucken, Germany
2
School of Materials Science and Engineering, Tianjin University, Tianjin, 300072, People’s Republic of China
in cancer therapy, as well as in computer hard disks in the electronics industry [8–11]. During the last couple of decades, the challenge of global optimization, i.e., the question of how to identify the structure of the global total-energy minimum of a system w
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