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

TL;DR

This study improves the accuracy of DFT calculations for CO adsorption on copper surfaces by applying a DFT+U correction, aligning theoretical predictions with experimental site preferences and energies.

Contribution

The paper introduces a DFT+U method to correct site preference predictions in CO adsorption on Cu surfaces, enhancing agreement with experimental data.

Findings

DFT+U corrects site preference predictions

Improved agreement with experimental adsorption energies

Small changes in geometrical and vibrational properties

Abstract

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