Energetics and kinetics of Ti clustering on neutral and charged C60 surfaces

Using ab initio spin density functional theory, we investigate the energetics and kinetics of Ti clustering on both neutral and charged C60 surfaces. We compare the formation energy of sparsely dispersed zero-dimensional (0D), compact single-layered two-dimensional (2D), and clustered three-dimensional (3D) TiN configurations as a function of cluster size (N⩽12) and further study the transformation kinetics between them. We find that 0D configuration is always less stable than that of 2D and 3D configurations and 0D to 2D transformation involves in a single Ti diffusion process with kinetic barrier of ⩽0.7eV. On the other hand, there exists a critical cluster size (NC) of NC=5, below which 2D layers are preferred to 3D clusters. Hole- or B-doping greatly enhance the Ti-fullerene interaction and lead to stronger dispersion of Ti atoms. Even so, for moderate charge doping (less than seven holes) the critical size of Ti atoms on neutral C60 surprisingly remains unchanged or only slightly increases to NC=6 by...