This competition is most clearly seen with the Offset structure S-Offset-H (figure ), which has large atomic migrations, relaxing to a 3D 3-atom structure. During relaxation the single separated atom is initially stable, whereas the two atom cluster which was initially ad-sorbed at H migrates to neighbouring sulphide atoms. In the formation of this cluster, the distance between the two atom cluster and the single atom decreases. Once this distance becomes ∼ 3.3 Å the single Cu atom begins to migrate away from the initially stable H site to form a 3 atom cluster. Once this three atom cluster forms, the central Cu atom rises upwards to form a 3D triangle structure (figure ).