MICROSCOPIC AND MACROSCOPIC ESTIMATES OF FRICTION - APPLICATION TO SURFACE-DIFFUSION OF COPPER

A comparison is presented between macroscopic constants relating to th e diffusion dynamics of a Cu atom on a Cu surface and their microscopi c estimates. Comparison of elastic constants, speed of sound and frict ion coefficient indicates that a generalized Langevin equation (GLE) d escription of the diffusion dynamics of the Cu adatom is quite reasona ble. This serves as a further justification for the recent GLE-based a nalysis of the experimental measurement of hopping distributions of me tal atoms on metal surfaces.