Van der Waals Interactions Between Organic Adsorbates and at Organic/Inorganic Interfaces

Tkatchenko, Alexandre; Romaner, Lorenz; Hofmann, Oliver; Zojer, Egbert; Draxl, Claudia; Scheffler, Matthias

doi:10.1557/mrs2010.581

Cited by 273 publications

(282 citation statements)

References 59 publications

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“…Under these conditions, although the short-range chemical interaction is responsible for the atomic contrast, vdW interactions control the absolute force scale. Force spectroscopy measurements thus offer the possibility to quantify these interactions and test the performance of novel theoretical descriptions [35] of the subtle nonlocal correlations responsible for the vdW forces.…”

Section: Prl 106 176101 (2011) P H Y S I C a L R E V I E W L E T T Ementioning

confidence: 99%

Forces and Currents in Carbon Nanostructures: Are We Imaging Atoms?

et al. 2011

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First-principles calculations show that the rich variety of image patterns found in carbon nanostructures with the atomic force and scanning tunneling microscopes can be rationalized in terms of the chemical reactivity of the tip and the distance range explored in the experiments. For weakly reactive tips, the Pauli repulsion dominates the atomic contrast and force maxima are expected on low electronic density positions as the hollow site. With reactive tips, the interaction is strong enough to change locally the hybridization of the carbon atoms, making it possible to observe atomic resolution in both the attractive and the repulsive regime although with inverted contrast. Regarding STM images, we show that in the near-contact regime, due to current saturation, bright spots correspond to hollow positions instead of atomic sites, providing an explanation for the most common hexagonal pattern found in the experiments. Fullerenes, nanotubes, graphene, and carbon nanoribbons are among the most promising materials for nanotechnological applications due to their unique mechanical and electronic properties [1,2]. Turning these expectations into real-world devices requires tools like the STM and the atomic force microscope (AFM) with true atomic resolution (FM-AFM) [3] to visualize, characterize, and manipulate these materials at the atomic scale. However, in spite of the apparent simplicity of the common honeycomb structure and the long-standing experimental research effort, we do not know yet something as fundamental as whether the maxima in the scanning probe microscopy images correspond to atoms or to the hollow sites [4][5][6][7]. Here, we use first-principles calculations to show that the rich variety of AFM and STM image patterns found in carbon nanostructures can be rationalized in terms of the chemical reactivity of the tip and the distance range explored in the experiments.The first STM images of the graphite(0001) surface did not display the expected honeycomb pattern but a hexagonal arrangement of bright spots (topographic maxima; see Fig. 1 in [8]) [9][10][11]. The accepted interpretation relies on a subtle electronic effect [12]. The Bernal stacking makes the two surface atoms inequivalent. C atoms, with a nearest neighbor right below in the second layer, do not contribute significantly to the density of states close to the Fermi level, and only the C atoms are imaged as bright spots at low bias voltages. Although a honeycomb pattern should be recovered for larger biases, the experimental evidence accumulated over the past 25 years [9][10][11][12][13] shows that STM images with a hexagonal pattern are overwhelmingly recorded over a broad range of bias voltages and distance operation conditions. Nevertheless, several groups have reported honeycomb patterns even for small bias voltage [13][14][15][16][17].The FM-AFM, relying on the forces between the tip and surface, is expected not to be so sensitive to electronic effects and to reflect the real atomic structure of the surface. However, the first reported ...

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Section: Prl 106 176101 (2011) P H Y S I C a L R E V I E W L E T T Ementioning

confidence: 99%

Forces and Currents in Carbon Nanostructures: Are We Imaging Atoms?

et al. 2011

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“…Such effects become especially pronounced in graphene/metal interfaces where weak van-der-Waals (vdW) interactions play a key role. Recently, several empirical vdW correction schemes were incorporated into DFT calculations 48 , the most popular being that of Grimme 49 , and TkatchenkoScheffler (TS) 50 . Both approaches are based on standard DFT with empirical vdW C 6 /r 6 atom-atom pairwise contributions multiplied by damping functions to switch off diverging vdW contributions at small interatomic distances.…”

Section: Computational Detailsmentioning

confidence: 99%

Atomic and electronic structure of simple metal/graphene and complex metal/graphene/metal interfaces

et al. 2012

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Atomic and electronic structure of simple metal/graphene and complex metal/graphene/metal interfaces Structural, electronic, and magnetic properties of simple interfaces (graphene on top of metallic substrate) and complex interfaces (a single metallic adlayer on a simple graphene/metal system, either on top or between the graphene and metallic substrate) have been studied using density functional theory. Two types of simple interfaces with strong (Ni/graphene) and weak (Cu/graphene) bonding were considered. In addition to binding energies and interface distances, which are used to quantify the strength of graphene-substrate interactions, the bonding in simple and complex interfaces was analyzed using charge density distributions and bond orders. Substantial enhancement of metallic substrate/graphene binding was observed in complex interfaces, consisting of Ni monolayer on top of simple {Ni or Cu}/graphene interface. The increase of substate-graphene bonding in such complex interfaces is accompanied by weakening in-plane C-C bonds in graphene, as quantified by the bond orders. A weak ferrimagnetism in graphene, i.e. unequal magnetic moments -0.04 µ B and +0.06 µ B on C atoms, is induced by a ferromagnetic Ni substrate. The strength of graphene-substrate interactions is also reflected in simulated STM images.

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“…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.…”

Section: Introductionmentioning

confidence: 99%

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

et al. 2013

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We present a benchmark study for the adsorption of a large π -conjugated organic molecule on different noble metal surfaces, which is based on x-ray standing wave (XSW) measurements and density functional theory calculations with van der Waals (vdW) interactions. The bonding distances of diindenoperylene on Cu(111), Ag(111), and Au (111) surfaces (2.51, 3.01, and 3.10Å, respectively) determined with the normal-incidence XSW technique are compared with calculations. Excellent agreement with the experimental data, i.e., deviations less than 0.1Å, is achieved using the Perdew-Burke-Ernzerhof (PBE) functional with vdW interactions that include the collective response of substrate electrons (the PBE + vdW surf method). It is noteworthy that the calculations show that the vdW contribution to the adsorption energy increases in the order Au(111) < Ag(111) < Cu(111).

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Van der Waals Interactions Between Organic Adsorbates and at Organic/Inorganic Interfaces

Cited by 273 publications

References 59 publications

Forces and Currents in Carbon Nanostructures: Are We Imaging Atoms?

Forces and Currents in Carbon Nanostructures: Are We Imaging Atoms?

Atomic and electronic structure of simple metal/graphene and complex metal/graphene/metal interfaces

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

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