Density Functional Theory Study Of The Interaction Of Small Transition Metal Cluster And NO,O₂

With the development of clusters research, the interaction of metal clusters withsmall gas molecules has attracted much attention. Small gas molecules colud changethe chemical and physical properties of metal clusters. Thus, it is expected to uncoverthe formation mechanism and the stability rule of the interaction between metalclusters and small gas molecules. These results would provide some theoreticalguidance for the application of these nano-sized metals.In this thesis, the structures, electronic properties of M₂NO （M=Sc to Zn）, TinO₂and TinO₂–（n=1–10） clusters have been studied by using the B3LYP hybrid densityfunctional. All the results are summarized as follows.Density-functional theory （DFT） has been used to calculate the interaction ofnitric oxide with3d metal dimmers （scandium through zinc） and determine theground-state geometrical configurations, electronic states and vibrational frequencies.Results are compared to the relevant experimental values and to other theoreticalinvestigations when available, and the overall agreement has been obtained. On goingfrom left to right side of the Periodic Table, the preference for the coordination modeof NO to transition-metal dimmers is from side-on-bonded mode （Sc, Ti, V）, viasemibridging （Cr）, to terminal （Mn, Fe, Co, Ni, Cu）. The N-O stretching vibrationalfrequencies in the ground states of M₂NO （M=Sc to Zn） increase generally from theleft to the right side of the Periodic Table, whereas the N-O bond lengths decreasegenerally. The binding energies exhibit an overall decrease trend. These general trendsin the interaction of nitric oxide with3d metal dimmers mirror the main features ofNO adsorption on transition metal surfaces.The interaction between Tinclusters and O₂have been studied by using theB3LYP hybrid density functional. The resulting geometries show that the twodissociative oxygen atoms remains on the surface of pure Tinclusters and does notchange the geometry of Tinsignificantly. The two oxygen atoms exist in the vicinityof TinO₂clusters, exhibiting an O-Ti-O connection in TinO₂. The geometries of thelowest-energy neutral and anionic clusters are similar, but the stability of anions ishigher than that of neutrals. The stability analyses show that TinO₂clusters have highstability, especially for TiO₂and Ti7O₂clusters. In addition, the ionization potentials,electron affinities, electron detachment energies, and energy gaps are carefully investigated and discussed. On the basis of the optimized structures, we investigateand discuss the magnetic properties of the two systems. It is found that there is acharge transfer from Ti atoms to O atoms and a strong interaction between Ti-3d,Ti-4s, and O-2p orbitals. The antiferromagnetic ordering is dominant in the twosystems. The magnetic moment of TinO₂is clearly dominated by the localized3delectrons of Ti atoms while two oxygen atoms contribute a very small amount of spinin TinO₂clusters.