Adsorbate vibration and resonance lifetime broadening of a cobalt adatom on a Cu(111) surface

Journal article, 2006

We present a theoretical calculation of the vibrational spectrum and resonance lifetime of Co/Cu(111) surface based on a well-tested empirical potential model. The phonon dispersions and local vibrational densities are obtained as a function of adsorbate coverage. The frequencies of the adsorbate-induced vibrational modes are in close agreement with those given by first-principles calculations and comparable with available experimental data. Analysis of the polarization distributions shows that both the frustrated translation (FT) and vertical vibration of the adsorbate are strongly coupled with atomic vibrations in the substrate. We also determined the lifetime of the FT mode caused by resonance broadening in the single-adsorbate limit. These results provide the basis for detailed study of nonadiabatic dynamics of vibrational excitation and damping of adatoms at metal surfaces.