The four sites in Pt(111) are composed of different numbers of Pt atoms: atop, bridge, fcc hollow and hcp hollow sites are 1-fold, 2-fold, 3-fold, and 3-fold sites, respectively, and they each have a unique energy of adsorption, which can vary as much as 0.12 eV (Figure ). Sequentially, when a configuration's average n-fold value falls below 2, it implies adsorbate configurations that are primarily located on atop sites, and an average n-fold value above 2 means they are mostly on hollow sites. As can be seen in Figure , the atop-NN and fcc-NN models stay in the atopsite-dominant region and hollow-site-dominant region, respectively, throughout the entire range of coverage. However, there indeed is a transition from adsorbates on mostly hollow sites to mostly atop sites across ∼0.5 ML coverage in the global minimum model. Previously, it was reported that the preferred adsorbate arrangements at different coverages entailed site-to-site conversion, which results in mixed-site occupation . The phenomenon has been explained by combinatory effects from a balancing between inherent, low-coverage site preference and keeping the furthest distance from each other to minimize through-space repulsion . Another explanation of the phenomena is provided by attractive dipolar interactions among opposite-signed atop site bound adsorbates and bridge/hollow site bound adsorbates . The adsorption configuration of CO on Co(0001) obtained from the global minima hopping procedure shows the opposite trend compared to the adsorption on Pt(111). In the low coverage limit, CO first occupies atop sites until a coverage of 3/9 th ML is reached. Then, the strong repulsive interaction of CO leads to a destabilization, resulting in the occupation of mostly bridge and 3fold hollow sites, as seen by the increase in the n-fold value. CO occupies the hcp sites at a full monolayer coverage. From DFT calculations using the revPBE functional, Gunasooriya et al. also observed that CO favors the atop sites until 1/3 ML coverage. Then, adsorption in higher coordinated sites is preferred. However, their most stable configuration at the monolayer coverage is in the bridge site. In our study, we performed relaxations with all CO adsorbates in bridge sites, but the structure always relaxed to the hcp configuration.