First-principles extrapolation method for accurate CO adsorption energies on metal surfaces

TL;DR

This paper introduces a first-principles correction method based on CO singlet-triplet excitation energies to accurately predict CO adsorption energies on various metal surfaces, improving agreement with experimental data.

Contribution

The study develops a linear correction approach using high-level quantum chemistry data to enhance DFT predictions of CO adsorption energies on metal surfaces.

Findings

Corrected adsorption energies match experimental values.

Method accurately predicts adsorption site preferences.

Linear relationship between adsorption energy and singlet-triplet splitting established.

Abstract

We show that a simple first-principles correction based on the difference between the singlet-triplet CO excitation energy values obtained by DFT and high-level quantum chemistry methods yields accurate CO adsorption properties on a variety of metal surfaces. We demonstrate a linear relationship between the CO adsorption energy and the CO singlet-triplet splitting, similar to the linear dependence of CO adsorption energy on the energy of the CO 2$\pi$* orbital found recently {[Kresse {\em et al.}, Physical Review B {\bf 68}, 073401 (2003)]}. Converged DFT calculations underestimate the CO singlet-triplet excitation energy $\Delta E_{\rm S-T}$, whereas coupled-cluster and CI calculations reproduce the experimental $\Delta E_{\rm S-T}$. The dependence of $E_{\rm chem}$ on $\Delta E_{\rm S-T}$ is used to extrapolate $E_{\rm chem}$ for the top, bridge and hollow sites for the (100) and (111) surfaces of Pt, Rh, Pd and Cu to the values that correspond to the coupled-cluster and CI $\Delta E_{\rm S-T}$ value. The correction reproduces experimental adsorption site preference for all cases and obtains $E_{\rm chem}$ in excellent agreement with experimental results.