Phase Diagram And Adsorption-Desorption Kinetics Of CO On Ru(0001): Present Limitations Of A First Principles Approach

TL;DR

This study uses a lattice gas model with DFT-derived interactions to analyze CO adsorption and desorption on Ru(0001), revealing limitations of first-principles methods in accurately predicting site preferences at higher coverages.

Contribution

It demonstrates the application of a lattice gas model combined with DFT to study phase diagrams and kinetics, highlighting current limitations in first-principles predictions for complex surface phenomena.

Findings

Good agreement with experiments below 1/3 ML coverage using top sites only.

Including hollow sites leads to incorrect predictions of binding energy differences.

DFT fails to accurately predict site preferences at higher coverages.

Abstract

A lattice gas model is used to study the equilibrium properties and desorption kinetics of CO on Ru(0001). With interactions obtained from density functional theory (DFT) the phase diagram and temperature programmed desorption (TPD) spectra are calculated up to a coverage of 1/3 ML using top sites only. For coverages beyond 1/3 ML hollow sites are included. Good agreement is obtained between experiment and theory for coverages below 1/3 ML using top sites only. When including hollow sites, DFT calculations fail in predicting the correct binding energy differences between top and hollow sites giving disagreement with TPD, low energy electron diffraction (LEED) and heat of adsorption experiments.