  Adsorption geometry and stability of organic molecules on surfaces are key
parameters that determine the observable properties and functions of hybrid
inorganic/organic systems (HIOSs). Despite many recent advances in precise
experimental characterization and improvements in first-principles electronic
structure methods, reliable databases of structures and energetics for large
adsorbed molecules are largely amiss. In this review, we present such a
database for a range of molecules adsorbed on metal single-crystal surfaces.
The systems we analyze include noble-gas atoms, conjugated aromatic molecules,
carbon nanostructures, and heteroaromatic compounds adsorbed on five different
metal surfaces. The overall objective is to establish a diverse benchmark
dataset that enables an assessment of current and future electronic structure
methods, and motivates further experimental studies that provide ever more
reliable data. Specifically, the benchmark structures and energetics from
experiment are here compared with the recently developed van der Waals (vdW)
inclusive density-functional theory (DFT) method, DFT+vdW$^{\mathrm{surf}}$. In
comparison to 23 adsorption heights and 17 adsorption energies from experiment
we find a mean average deviation of 0.06 \AA{} and 0.16 eV, respectively. This
confirms the DFT+vdW$^{\mathrm{surf}}$ method as an accurate and efficient
approach to treat HIOSs. A detailed discussion identifies remaining challenges
to be addressed in future development of electronic structure methods, for
which the here presented benchmark database may serve as an important
reference.
