Diffusion processes of trimers on missing row surfaces: Cu3Ag (110) and Ag3 Cu(110)

Abstract

A semi-empirical potential according to the embedded atom, has been applied to investigate the diffusion of trimers by computing the energy barriers for different mechanisms. Our attention was more focused on the leapfrog process which is likely to occur on missing row surfaces. The activation barriers of this mechanism are calculated using drag method at 0K. These barriers are found to be 0.64 and 0.68 eV for hopping out the channel for Cu3Ag (110) and Ag3 Cu(110) and Ag 3 / Cu (110) respectively. While for hopping down at the other side they are about 0.42 and 0.32 eV. Moreover, a deep metastable position is observed during leapfrog diffusion leading to some spectacular trimer motion. At high temperature and essentially for Cu 3Ag (110) and Ag3 Cu(110), we also observed a competition between leapfrog process and concerted jump mechanism with a deformation of trimer geometry. Implications of these findings are briefly discussed. © 2013 Springer Science+Business Media New York.