Using molecular dynamics simulations and a modified analytic embedded atom potential, the self-diffusion dynamics of Pd adatoms and dimers on the Pd(001) surface were studied at 600 to 900K. The simulation time varies from 25 to 50ns according to the different substrate temperature. The diffusion mechanism of both the single Pd adatoms and dimers was the simple exchange mechanism with the substrate atoms. The diffusion pre-factors D0 and activation energies Ea were derived from the Arrhenius relationship. The activation energy Ea was in good agreement with the results of quench molecular dynamics and experimental data on single Pd adatoms. The activation energy (0.58eV) of the dimer was slightly lower than that 0.63eV of the single adatom because of the higher coordination numbers. When substrate temperature was 290K, the diffusion mobility of the single adatom was equal to that of the dimer. In addition, the remarkable self-diffusion behaviors in several previous experiments, that the diffusion mobility of the dimer was higher than that of the single adatom at low temperatures, were explained in terms of the present molecular dynamics results.

Self-Diffusion Behaviors of Pd Adatom and Dimer on Pd(001) Surface. Liu, F., Hu, W., Deng, H., Xiao, S., Li, X., Luo, W., Yang, J.: Computational Materials Science, 2009, 47[2], 501-5