First-principles calculations for titanium monoxide clusters Ti_nO (n=1--9)

Based on the density-functional theory, this paper studies the geometric and magnetic properties of Ti_nO (n=1--9) clusters. The resulting geometries show that the oxygen atom remains on the surface of clusters and does not change the geometry of Ti_n significantly. The binding energy, second-order energy differences with the size of clusters show that Ti_7O cluster is endowed with special stability. The stability of Ti_nO clusters is validated by the recent time-of-flight mass spectra. The total magnetic moments for Ti_nO clusters with n=1--4, 8--9 are constant with 2 and drop to zero at n=5--7. The local magnetic moment and charge partition of each atom, and the density of states are discussed. The magnetic moment of the Ti_nO is clearly dominated by the localized 3d electrons of Ti atoms while the oxygen atom contributes a very small amount of spin in Ti_nO clusters.