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dc.contributor.advisor Ngoepe, P.E. Mahladisa, Mokete Abram
dc.contributor.other Ackermann, L. 2013-04-08T13:50:56Z 2013-04-08T13:50:56Z 2011
dc.description Thesis (Ph.D. (Physics)) --University of Limpopo, 2011 en_US
dc.description.abstract The importance of gold for scientific uses is of fundamental importance to research and technology developments. The bulk gold shows reluctance to participate in chemical reactions, the effect which has been corrected by the change in the size towards nanoclusters. It is therefore imperative that the structure of gold nanomaterials is understood for better applications in catalysis and other developments. Molecular dynamics and the density functional theory have proven to be good tools in computational material science and have thus been used to greater lengths. Molecular dynamics simulations on different gold nanoclusters and nanotubes were successfully carried out at different thermodynamic conditions. The effect of size on the melting of materials was duly tested and our results to some extend agree with what has already been reported. Gold nanoclusters show melting below the bulk and the melting temperatures increase with cluster size. However, the Au55 cluster shows different results in that it melts above the bulk due to structural reconstruction. The structure of the clusters changes from spherical shapes to tetragonal or face centred cubic (fcc) structures. Gold nanotubes show no resistance to temperature and different configurations are obtained in different ensembles. Single wall nanotubes form spherical clusters in the NVT while the NPT conditions give patches of clusters at elevated temperatures. The multi wall nanotubes also form spherical clusters in the NVT but fcc structures are obtained in the NPT Berendsen ensemble towards melting. Ab initio calculations in DMOL3 code on different gold nanoclusters show the stability of the clusters to increase with size and the Au3 and Au8 clusters contain the most stable structures. The Au-Au bond length in the dimer was obtained to within reasonable agreement with experiments and other theoretical works. Doping of the clusters further improved their stability although different impurities give different observations. The QMERA code calculations show that a gold atom on top of the surface causes slanting of the outer MD layers. The morphology of the quantum atoms also changes as compared to the neutral surface and the results are compared by the DMOL3 code which confirms the QMERA results. en_US
dc.description.sponsorship Mintek, and the National Research Foundation en_US
dc.format.extent xiv, 184 leaves : ill. en_US
dc.language.iso en en_US
dc.publisher University of Limpopo (Turfloop Campus) en_US
dc.relation.requires pdf en_US
dc.subject Computer modelling studies en_US
dc.subject Gold nanoclusters en_US
dc.subject Gold nanotubes en_US
dc.subject Gold nanowires en_US
dc.subject.ddc 669.22 en_US
dc.subject.lcsh Mines and mineral resources -- South Africa en_US
dc.subject.lcsh Gold metallurgy en_US
dc.subject.lcsh Nanotechnology en_US
dc.title Computer modelling studies of gold nanoclusters, nanotubes and nanowires en_US
dc.type Thesis en_US

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