Molecular dynamics study of structure and stability in Au nanoparticles

Gold nanoclusters have been shown to be a most promising nanomaterial with a wide range of potential applications in electronics, bio-medicine, optics and catalysis. Critical parameters that effect the electronic, optical and catalytic properties of these nanoclusters are their size and shape. Therefore understanding the mechanisms underlying the crystallization of these nanoclusters is important if one hopes to control their size and morphology. In this thesis we provide an insight into the structural ordering of the atoms comprising gold nanoclusters quenched from the melt down to 298K. We use standard structural measures such as the Q6 order parameter and ring statistics to measure the degree of crystallization during quenching. We also to visualize the time evolution of structural ordering of the nanocluster core at the temperature where significant crystallization first occurs, using a newly developed, topological measure, based on planar graphs.<br><br>This study provides new evidence of crystallization of the surface preceding that of the core, which is currently a point of debate in the literature. We also give, for the first time, evidence of HCP twin planes forming directly below the region where the edges of two (111) surface planes meet in the formation of a defected icosahedral cluster.<br>The results of this thesis have been published in 4 refereed international journals and discussed at a number of national and international conferences.