Coincidentally, the interaction energy oscillation period is also much smaller for the Cu(111) surface in comparison to the Ag(111), namely 17 Å and 38 Å, respectively. The authors used the theory by Hyldgaard and Persson 49 (see section 3.7 of this review) to fit their results. Theoretical and experimental potentials matched very well. This fact, along with the coincidence of interaction energy oscillation periods for all the studied systems with The dotted line represents a fit using theory by Hyldgaard and Persson (see section 3.7 of this review, please). those expected for the FOs , allows for a conclusion on the origin of the surface interaction between the adsorbates.