CO adsorption on Cu(111) and Cu(001) surfaces: improving site preference in DFT calculations

摘要

CO adsorption on Cu(111) and Cu(001) surfaces has been studied withinab-initio density functional theory (DFT). The structural, vibrational andthermodynamic properties of the adsorbate-substrate complex have beencalculated. Calculations within the generalized gradient approximation (GGA)predict adsorption in the threefold hollow on Cu(111) and in the bridge-site onCu(001), instead of on-top as found experimentally. It is demonstrated that thecorrect site preference is achieved if the underestimation of the HOMO-LUMO gapof CO characteristic for DFT is correct by applying a molecular DFT+U approach.The DFT+U approach also produces good agreement with the experimentallymeasured adsorption energies, while introducing only small changes in thecalculated geometrical and vibrational properties further improving agreementwith experiment which is fair already at the GGA level.