ELECTRON-HOLE PAIR CONTRIBUTIONS TO SCATTERING, STICKING, AND SURFACE-DIFFUSION - CO ON CU(100)

To assess the importance of coupling to electron-hole pair (ehp) excit ations for molecular sticking, scattering, and diffusion dynamics at m etal surfaces, simulations of the CO/Cu(100) system were performed usi ng the ''molecular dynamics with electronic frictions'' method. Over a range of incident translational energies, energy losses to ehp excita tions produce a moderate increase in sticking probability and account for 5%-10% of initial translational energy in scattered molecules, sig nificantly less than phonon losses. Vibrational excitation and deexcit ation of scattered molecules, while remaining a minor pathway for ener gy flow, is strongly affected by the inclusion of ehp excitations. Fin ally, although equilibrium diffusion constants are unaffected by the i nclusion of coupling to ehp, it causes a significant quenching of tran sient mobility following adsorption of translationally hot molecules. (C) 1998 American Institute of Physics.