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Computational studies of clusters

Nan Shao, University of Nebraska - Lincoln

Abstract

As we know, synergy between theory and experiment plays a more and more crucial role in the investigations of molecular structures. My research of this work focused on the theoretical prediction of the structures and properties for the nanoclusters by using unbiased basin-hopping (BH) global optimization combined with density functional theory (DFT) and ab initio quantum calculations, of which the results are compared to and used to guide experiments.^ Generally, fullerene means hollow carbon cage with only hexagons and pentagons on the surface. Since the discovery of the typical fullerene “Buckyball” C60, fullerene chemistry has developed into a mature field. Recently, experimental efforts have increasingly been devoted to the larger fullerenes such as C98 – C120. Therefore, we have studied larger fullerene C82 – C120 and predicted the best candidates with the lowest electronic energy at DFT level for the first time.^ The fantastic icosahedral Zintle clusters, Sn12 2- and Pb122- have been synthesized in the laboratory in 2006, named as stannaspherene and plumbaspherene, respectively. However, the global-minimum structures of other Zintl clusters Si122- and Ge12 2- are still unknown. In this work, we disclosed the low-lying structures of group-14 dianionic clusters Si122-, Ge12 2- and Sn122- Electronic and aromatic properties of the low-lying structures of Si12 2- and Ge122- have also been studied.^ Homoleptic gold thiolate clusters (AuSR)N (N = 6-12) were studied by using a global-minimum search method. Onset of a new structural family of double helical structures in small-sized gold thiolate clusters and the separate-ring structures in larger clusters is revealed. The double helical structure suggests a new folding way for flexible gold thiolate clusters.^ It is well known that gold nanoclusters possess novel properties that can be exploited for applications in catalysis and biology. Theoretical scientists have applied the first-principle method to study this reaction thoroughly in order to gain more insightful understanding and to suggest better efficient catalysts. Gold clusters with different structures such as cage-like, tubular and compact core-shell structures can be very competitive with each other, particularly near major structural transition points. It is still very challenging to make unambiguous determination of the structure for the global minima. This work explored the structural evolution of gold anion clusters Au n- (n = 27 to 35) and cooperated with a new experimental technique.^ A large number of experiments found that the small gold clusters, with the number less than 20, isolated or soft-landed on the metal oxide support, have the catalytic ability at low temperature. Previous studies are all based on the pure gold clusters and the impurity effects were studied very scarcely. So, in this work, the catalytical ability of six metal-endohedral gold-cage clusters, namely, W@Au12, Nb@Au13, Zr@Au14, Sc@Au15, Ca@Au16, and Na@Au17 have been studied by DFT method. The CO oxidation reaction is applied as a benchmark test to probe the catalytic capability.^

Subject Area

Chemistry, Physical

Recommended Citation

Shao, Nan, "Computational studies of clusters" (2010). ETD collection for University of Nebraska - Lincoln. AAI3411964.
http://digitalcommons.unl.edu/dissertations/AAI3411964

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