Diffusion of Cu adatoms and dimers on Cu(111) and Ag(111) surfaces

TL;DR

This paper investigates the diffusion mechanisms of Cu adatoms and dimers on Cu(111) and Ag(111) surfaces using ab-initio calculations, revealing complex behaviors influenced by surface lattice differences and temperature-dependent parameters.

Contribution

It provides a detailed analysis of dimer diffusion processes and compares them with single adatom diffusion on two different metal surfaces, highlighting the effects of surface lattice constants.

Findings

Dimer diffusion involves complex translational and rotational moves.

Diffusion coefficients vary significantly between Cu(111) and Ag(111).

Energy barriers and prefactors are temperature dependent for dimers.

Abstract

Diffusion of Cu adatoms and dimers on Cu(111) and Ag(111) surfaces is analyzed basing on ab-initio surface potentials. As compared to the simple single adatom jumps that alternate between two states, dimers undergo more complex diffusion process that combines translational and rotational moves. Diffusion coefficients for these processes on both surfaces are calculated and compared with diffusion of single particle. The main parameters of diffusion coefficient: energy barrier and prefactor become temperature dependent when dimer moves jumping between many positions of different values of energy. Small difference in the surface lattice constant for Cu and Ag crystal results in completely different energy landscape for dimer jumps and as an effect different diffusion process. At the same time single adatom diffusion does not change so much.