Vibrational recognition of adsorption sites for CO adsorbed on transition-metal surfaces

We have studied the vibrational properties of carbon monoxide adsorbed on transition-metal surfaces, using density-functional perturbation theory in the GGA-PBE approximation. The full dispersions for CO adsorbed on high-symmetry surface sites have been calculated, obtaining excellent agreement with spectroscopic measurements. This agreement in predicting absolute frequencies and frequency shifts as a function of the adsorption site is at variance with the poor performance of most exchange- correlation functionals in describing the energetics of adsorption. We provide a simple physical picture justifying this accuracy. These results open the possibility to directly connecting experimental vibrational spectra with the microscopic details of adsorption geometries.