Quantifying lateral adsorbate interactions by kinetic Monte-Carlo simulations and density-functional theory: NO dissociation on Rh(100)

Abstract

The dissociation of NO on Rh(100) surfaces has been modelled by kinetic Monte-Carlo (MC) simulations including nearest neighbour (NN) and next-nearest neighbour (NNN) interactions, and zero-coverage kinetic parameters obtained from experiments. Two approaches were performed to derive the lateral interactions. First, the interactions were quantified by fitting the MC model to the experimental data. All interactions between NO, N and O were found to be repulsive. Nearest-neighbour interactions involving atoms are typically on the order of 20–30 kJ mol⁻¹; between molecules they are below 10 kJ mol⁻¹. All next-nearest neighbour interactions were smaller than 10 kJ mol⁻¹. The simulations show that at higher initial NO coverage, the nitrogen and oxygen atoms were created by dissociation form c(2 × 2) islands, thereby compressing the NO areas and impeding their dissociation. Second, interactions estimated using DFT calculations were significantly higher than the ones estimated from fitting the experiments. Monte-Carlo simulations based on interactions obtained from DFT provide a description that is only qualitatively useful.