Structure Stability Of TiAu₄ Nanocluster With Water Adsorption

Aurum cluster is widely researched because of its high inoxidizability and thermal stability. The potential reactivity of aurum cluster when the size of aurum cluster is similar to 1 nanometer also attracts broad attention. The properties of aurum were changed by the doping of titanium. The interaction between alloy TiAu₄ and water molecules was studied in this dissertation.The possibly existent structures of TiAu₄ contacting with one,two,three or four water molecules were searched using basin-hopping program. Then the four most stable structures were optimized at first principle level.It was found that highly symmetrical Td structure which is stable in the vacuum was destroyed as well as the bounding was formed between titanium atoms that were pushed to the surface of alloy and the hydroxyl that were divorced from water molecules when the TiAu₄ clusters contacted with water molecules. Different properties were observed and the stable structure converted between two-dimensional structure and three-dimensional structure when the number of water molecules was changed. It is also possibly that TiAu₄ clusters were dissolved by water molecules if amount of water molecules was used.Considering that Van der Waals force possibly destroy the whole structure since the interaction between water molecules and metal is weak, the effects to different structure of Van der Waals force was researched. The small influence of Van der Waals to the whole structure was proved by the small change of the stable structure and relative stability. It is notably that the effect of Van der Waals to the whole structure was increased by the increasing number of water molecules.The structure with dissociative adsorption which was the main form when the water contacted the TiAu₄ clusters was more stable than the structure with molecular adsorption. It was found that was easily dissolved from the surface of TiAu₄ clusters since the dissociation energy is low. Thus TiAu₄ can be used as catalyzer in some hydrolysis action.