SUBSTRATE-ADSORBATE COUPLING IN COADSORBED COPPER

The vibrational properties of carbon monoxide adsorbed to the copper ( 100) surface are explored within density-functional theory. Atoms of t he substrate and adsorbate are treated on an equal footing in order to examine the effect of substrate-adsorbate coupling. This coupling is found to have a significant effect on the vibrational modes, particula rly the in-plane frustrated translation, which mixes strongly with sub strate phonons and broadens into a resonance. The predicted lifetime d ue to this harmonic decay mechanism is in excellent quantitative agree ment with experiment.