Structures and vibrational frequencies of CO adsorbed on transition metals from calculations using the vdW-DF2 functional

We confirmed how well the exchange-correlation functional vdW-DF2, with its non-local correlation part, describes the adsorption of CO on close-packed surfaces and clusters of Co, Ni, Cu, Ru, Rh, Pd, and Pt. The calculated adsorption energies are fairly close to the experimental values. The carbonyl vibrational frequencies, calculated within the harmonic approximation, systematically underestimate the experimental results. To amend this deficiency, we explored multiplicative and additive correction schemes. Scaling the calculated harmonic CO frequencies by a uniform factor of 1.030 yields results with a mean absolute deviation of ~13cm^-1 from experiment. With this correction scheme we were able to clarify some controversial structures for CO adsorption on the surfaces Pd(111) and Co(0001).