Using PBE/PAW, the adsorption energy (per COad molecule) decreases from 2.06 eV to 1.04 eV. The drastic decrease in adsorption energy is even more obvious when using the differential adsorption energy 𝐸 𝑎𝑑,𝑑𝑖𝑓𝑓 , which for addition of a second COad molecule is only 0.02 eV. With this low value, the formation of multicarbonyl species on these sites can be excluded at finite temperatures, even though these Pt1 sites are more strongly binding than Pt atoms on Pt(111) and even though the COad molecules can reduce the COad -COad repulsion by a significant tilt. This agrees with the experimental situation in so far as the formation of multicarbonyl species has rarely been proposed for Pt nanoparticle catalysts, in contrast, e.g., to multicarbonyl formation on Ru nanoparticles. .