Surface Geometry of $\mathrm{C}_{60}$ on Ag(111)*

The geometry of adsorbed $\mathrm{C}_{60}$ influences its collective properties. We report the dynamical low-energy electron diffraction and scanning tunneling microscopy studies to determine the geometry of a $\mathrm{C}_{60}$ monolayer, Ag(111)-($2\sqrt{3}\times 2\sqrt{3}$)$30\,^{\circ}$-$\mathrm{C}_{60}$ and related density functional theory calculations. The stable monolayer has $\mathrm{C}_{60}$ molecules in vacancies that result from the displacement of surface atoms. $\mathrm{C}_{60}$ bonds with hexagons down, with their mirror planes parallel to that of the substrate. The results indicate that vacancy structures are the rule rather than the exception for $\mathrm{C}_{60}$ monolayers on close-packed metal surfaces and closely related to the anneal.