Structure and Energetics of Azobenzene on Ag(111): Benchmarking Semiempirical Dispersion Correction Approaches

Abstract

We employ normal-incidence x-ray standing wave and temperature programed desorption spectroscopy to derive the adsorption geometry and energetics of the prototypical molecular switch azobenzene at Ag(111). This allows us to assess the accuracy of semiempirical correction schemes as a computationally efficient means to overcome the deficiency of semilocal density-functional theory with respect to long-range van der Waals (vdW) interactions. The obtained agreement underscores the significant improvement provided by the account of vdW interactions, with remaining differences mainly attributed to the neglect of electronic screening at the metallic surface.

Structural and electronic properties of the Ptn–PAH complex (n = 1, 2) from density functional calculations

“…Density functional theory (DFT) has become an invaluable tool in studying the interaction between metal clusters and graphene at the atomic level [9][10][11][12][13][14][15] . However, when considering this type of interaction, the effect of dispersion forces becomes important, as for example in the adsorption of aromatic molecules on metal surfaces [41][42][43][44][45][46][47] . The standard generalized gradient approximation (GGA) functionals, such as the Perdew-BurkeErnzerhof (PBE) 48 functional, do not describe this effect, since it cannot describe electron correlation in situations where the electronic densities of the molecule and surface in practice do not overlap and the dispersion interaction become dominant 41,49 .…”

Adsorption of tris(8-hydroxyquinoline)aluminum molecules on cobalt surfaces

“…In principle, the DFT-D scheme is fairly good for neutral organic systems, because atoms with the same atomic number tend to have very similar dispersion coefficients in these systems 67 . However, the DFT-D scheme could introduce problems for metal surfaces because the screening effect, which reduces the effective polarizability of metals that are far away from the surface, is not included 43,68 .…”

Exploring the bonding of large hydrocarbons on noble metals: Diindoperylene on Cu(111), Ag(111), and Au(111)

“…Here, x-ray standing wave (XSW) measurements can provide an important test for DFT calculations. 2,7 This is particularly important for systems with strong vdW contributions to the overall bonding, for which no simple substrate dependence is expected.…”

“…During recent years, huge efforts have been made to incorporate vdW interactions into density functional theory (DFT) calculations in order to determine the structure and stability of π -conjugated organic molecules on solid surfaces. [1][2][3][4][5][6] Understanding these interface properties is relevant, inter alia, for electron transfer processes in organic devices. Until now and despite the obvious benefit, there are only a few studies of metal-organic interfaces combining theory and experiment.…”