Strain effects on the binding and diffusion energies of Au adatoms and CeO2 admolcules on Au, CeO2, MgO and SrTiO3 surfaces

TL;DR

This study uses DFT calculations to analyze how elastic strains influence the binding and diffusion energies of Au adatoms and CeO2 admolecules on various oxide surfaces, revealing significant surface-dependent effects.

Contribution

It introduces a linear fitting scheme for strain-dependent binding and diffusion energies applicable to modeling surface processes under strain.

Findings

Strain significantly affects binding and diffusion energies across different surfaces.

Strain induces anisotropy in diffusion pathways depending on crystallographic orientation.

The linear model for energies under strain agrees well with DFT calculations up to 0.5% strain.

Abstract

First-principles density functional theory (DFT) calculations were used to study the effects of elastic strains on the binding and diffusion activation energies of Au adatom and CeO2 admolecule on Au (001), Ce-terminated CeO2 (001), MgO (001), SrO- and TiO2-terminationed SrTiO3 (001) surfaces. In preparation for computing these energies, normal and shear strains within the range 0.15% were applied in the plane of the surface of the supercell prior to placing the adsorbed species on the surface. Our study shows that the dependence of binding energies and diffusion barriers of adatoms and molecules on the strain varies significantly among surfaces. The strain was found to alter the symmetry of surface diffusion pathways causing anisotropy of the diffusion barriers. This strain-induced anisotropy depends on the orientation of the applied strains relative to the in-plane crystallographic directions of the free surface. The binding and diffusion activation energies were fit linearly in terms of strain components in the range 0.15% and the extrapolated values compared favorably to DFT computed values up to 0.5%. The scheme presented here for the computation and fitting of the binding and diffusion energies in terms of strain can be used to inform models of surface diffusion, clustering and growth of multi-component and multi-phase thin films and investigate the effect of strain on the self-organization in such systems.