Adsorption and dissociation of O$_{2}$ at Be(0001): First-principles prediction of an energy barrier on the adiabatic potential energy surface

TL;DR

This study uses first-principles calculations to analyze how O₂ molecules adsorb and dissociate on Be(0001), revealing an energy barrier in the dissociation process unlike other simple sp metals.

Contribution

It provides the first detailed prediction of an energy barrier for O₂ dissociation on Be(0001) using ab initio methods, highlighting unique surface chemistry features.

Findings

The most stable chemisorbed molecular state involves electron transfer between O₂ and Be surface.

The T-Y channel is most favorable for O₂ dissociation on Be(0001).

An energy barrier exists for O₂ dissociation at Be(0001), unlike other simple sp metals.

Abstract

The adsorption and dissociation of O$_{2}$ molecules at the Be(0001) surface is studied by using density-functional theory within the generalized gradient approximation and a supercell approach. The physi- and chemisorbed molecular precursor states are identified to be along the parallel and vertical channels, respectively. It is shown that the HH-Z (see the text for definition) channel is the most stable channel for the molecular chemisorption of O$_{2}$. The electronic and magnetic properties of this most stable chemisorbed molecular state are studied, which shows that the electrons transfer forth and back between the spin-resolved antibonding $\pi^{\ast}$ molecular orbitals and the surface Be $sp$ states. A distinct covalent weight in the molecule-metal bond is also shown. The dissociation of O$_{2}$ is determined by calculating the adiabatic potential energy surfaces, wherein the T-Y channel is found to be the most stable and favorable for the dissociative adsorption of O$_{2}$. Remarkably, we predict that unlike the other simple $sp$ metal surfaces such as Al(111) and Mg(0001), the \textit{adiabatic} dissociation process of O$_{2}$ at Be(0001) is an activated type with a sizeable energy barrier.