title: Self-diffusion of small clusters on fcc metal (111) surfaces
abstract: We use ab initio density-functional theory supplemented with the embedded-atom method to study the self-diffusion of small clusters on the (111) surface of eight fcc metals. A zigzag motion is found to be important in the dimer and tetramer diffusions. The dimer diffuses by a zigzag and concerted motion. The trimer diffuses by a concerted three-atom motion. The tetramer diffuses through a zigzag motion where only two atoms move simultaneously in each step. Thus, instead of increasing, the migration energy is lowered (or stays constant) for the tetramer as compared to that for the trimer. This novel break of the upwards trend in migration energy is predicted to be a general phenomenon.
authors.affiliation: National Center for High-Performance Computing, Hsinchu, Taiwan 30043, Republic of China.
authors.initials: CM
authors.lastname: Chang
authors.initials: CM
authors.lastname: Wei
authors.initials: SP
authors.lastname: Chen