Theoretical study of adatom self-diffusion on metallic fee {001} surfaces

Based on the discrete variational method with the local-density-functional approximation (DV-LDA), we propose molecular cluster models to simulate the physical surface with and without an adsorbed atom respectively. Our DV-LDA calculations favor the atomic exchange process along the [100] direction for Al self-diffusion on Al fee (001) surfaces and the atomic bridge hopping process along the [110] direction for Cu self-diffusion on Cu fcc (001) surfaces. Based on all available experimental and theoretical results, there is an interesting parameter which can correlate the favored self-diffusion mechanism on metallic fcc {001} surfaces.