eV. The most thermodynamically stable ethylene-Pt7 structures correspond to ethylene bound to the LM1 isomer of Pt7 (Fig. ), aligning well with our previous findings. LM1, which lies just ~0.09 eV above the prismatic Pt7 GM, has a single-layer structure with all its Pt atoms exposed and available for adsorbate binding, while the prismatic GM structure has a central Pt atom that is caged beneath the surface layer, unable to participate in adsorbate binding. As shown in Fig. , ethylene binding to the GM of Pt7 is ~0.6 eV weaker, such that the most stable such structure is nearly 0.7 eV above the most stable ethylene-LM1 structure. Indeed, even ethylene-Pt7 structures based on the Pt7 LM2 (ΔE = 0.15 eV) are more stable than those in which Pt7 is assumed to retain the prismatic GM structure.