Coadsorption of CO and O on Ru(0001): A structural analysis by density functional theory

TL;DR

This study uses density functional theory to analyze the atomic structures of coadsorbed CO and O on Ru(0001), confirming previous experimental results and predicting new stable phases.

Contribution

It provides detailed DFT-based atomic geometries for four coadsorbate phases on Ru(0001), including two validated by LEED and two novel predictions.

Findings

Good agreement between DFT and LEED structures for two phases

Predicted atomic structure for a previously uncharacterized phase

Identified a new stable ordered mixed phase

Abstract

Knowledge of the atomic geometry of a surface is a prerequisite for any detailed understanding of the surface's electronic structure and chemical properties. Previous studies have convincingly demonstrated that density functional theory (DFT) yields accurate surface atomic geometries and that reliable predictions concerning stable and metastable phases can be made on the basis of the calculated energetics. In the present work we use DFT to investigate the atomic structure of four ordered coadsorbate phases of carbon monoxide and oxygen on Ru(0001). All of the structures have a (2x2) periodicity with differing concentrations of CO molecules and O atoms. For two of these phases dynamical low-energy electron diffraction (LEED) intensity analyses have been performed and the agreement between our DFT- and the LEED-determined structures is found to be very good. We predict the atomic geometry of the third phase for which no structural determination based on experiments has been made to date. We also predict the stability of a new ordered mixed phase.