Aromatic molecules on low-index coinage metal surfaces: Many-body dispersion effects.

Yingda Jiang,Wei Liu,Sha Yang,Shuang Li

doi:10.1038/srep39529

Yingda Jiang, Wei Liu + Show 2 more

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https://doi.org/10.1038/srep39529

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Abstract

Understanding the binding mechanism for aromatic molecules on transition-metal surfaces in atomic scale is a major challenge in designing functional interfaces for to (opto)electronic devices. Here, we employ the state-of-the-art many-body dispersion (MBD) approach, coupled with density functional theory methods, to study the interactions of benzene with low-index coinage metal surfaces. The many-body effects contribute mostly to the (111) surface, and leastly to the (110) surface. This corresponds to the same sequence of planar atomic density of face-centered-cubic lattices, i.e., (111) > (100) > (110). The binding energy for benzene/Au(110) is even stronger than that for benzene/Ag(110), due to a larger broadening of molecular orbitals in the former case. On the other hand, our calculations show almost identical binding energies for benzene on Ag(111) and Au(111), which contradicts the classic d-band center theory that could well predict the trend in chemisorption energies for various small molecules on a number of metal surfaces. Our results provide important insight into the benchmark adsorption systems with opener surfaces, which could help in designing more complex functional interfaces.

Highlights

IntroductionTo better understand the nature of bonding for aromatic molecules on low-index metal surfaces, here we systematically study the adsorption of benzene on the (110), (100), and (111) surfaces of Cu, Ag, and Au. Our calculations show that the many-body dispersion (MBD) effects play a prominent role for all studied systems, reducing the binding energies by at most 0.26 eV for Cu(111) compared to the data from the pairwise DFT+vdWsurf method[34]
The contribution of many-body dispersion (MBD) effects in different systems is closely related to their corresponding planar atomic density of face-centered cubic (FCC) metals, which is defined as the fraction of total crystallographic plane area that is occupied by atoms
The adsorption energy, Ead, of benzene on metal surfaces was determined by, Ead = EBz/M − EM − EBz where EBz/M, EM, and EBz denotes the total energy of the adsorption system, the relaxed bare metal slab, and the relaxed gas-phase benzene, respectively

Summary

Introduction

To better understand the nature of bonding for aromatic molecules on low-index metal surfaces, here we systematically study the adsorption of benzene on the (110), (100), and (111) surfaces of Cu, Ag, and Au. Our calculations show that the MBD effects play a prominent role for all studied systems, reducing the binding energies by at most 0.26 eV for Cu(111) compared to the data from the pairwise DFT+vdWsurf method[34]. The binding energy for benzene/Au(110) is even stronger than that for benzene/Ag(110), which somewhat against our intuition that Ag surfaces are more reactive (or at most equal stable) than Au surfaces This finding can be well explained by extent of broadening and splitting of the molecular orbitals of the adsorbate near the Fermi level. Given to the fact that the d-band center of Au(111) is significantly closer to the Fermi level than that of Ag(111), our observations seem to contradict the classic d-band center theory of Hammer and Nørskov[35]

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