Abstract
The electronic properties of azobenzene (AB) in interaction with gold clusters and adsorbed on the Au(111) surface are investigated by adopting a near-Hartree-Fock-Kohn-Sham (HFKS) scheme. This scheme relies on a hybrid Perdew-Burke-Ernzerhof functional, in which the exact non-local HF exchange contribution to the energy is taken as 3/4. Ionization energies and electron affinities for gas phase AB are in very good agreement with experimental data and outer valence Green's function) calculations. The presence of C-H⋯Au interactions in AB-Aun complexes illustrates the role played by weak interactions between molecular systems and Au nanoparticles, which is in line with recent works on Au-H bonding. In AB-Aun complexes, the frontier orbitals are mainly localized on the gold platform when n ≥ 10, which indicates the transition from a molecular to a semiconducting regime. In the latter regime, the electronic density reorganization in AB-Aun clusters is characterized by significant polarization effects on the Au platform. The accuracy of the near-HFKS scheme for predicting adsorption energies of AB on Au(111) and the interest of combining exact non-local HF exchange with a non-local representation of the dispersion energy are discussed. Taking into account the significant computational cost of the exact non-local HF exchange contribution, calculations for the adsorption energies and density of states for AB adsorbed on Au(111) were carried out by using a quantum mechanics/molecular mechanics approach. The results strongly support near-HFKS as a promising methodology for predicting the electronic properties of hybrid organic-metal systems.
Highlights
Some emphasis was placed on the determination of the electronic energy levels at the organic/metal interface,26 which define the density of states (DOS) as well as the electrochemical properties of the scitation.org/journal/jcp hybrid system
PBE combined with the Grimme empirical correction for dispersion energy (D3)51 was used in all the geometry optimizations, which were carried out with the triple-ζ (TZVP-MOLOPT-Goedecker– Tetter–Hutter (GTH)) and double-ζ shorter-range (DZVP-MOLOPT-SR-GTH) basis sets optimized for molecular calculations67 for the AB and Au atoms, respectively
PBEX-D3 results for the ionization energies and electron affinities of t-AB are in very good agreement with experimental data
Summary
The chemistry of the gold surface is of fundamental importance in material- and nanoscience. In this context, the interactions between organic molecules and gold nanoparticles have been found highly dependent on the size/shape of the metallic surface. Gold nanoparticles are very important in nanoplasmonics and catalysis. Of particular interest are the electrochemical properties of gold nanoparticles, the supramolecular control of photoswitching on gold nanoparticles, and the chemical reactivity of gold aggregates supported on different platforms.14,15Several works sought to elucidate the physics at play at the interface by studying the adsorption of organic molecules on the gold metallic surface. The understanding of the adsorption processes involves the correct description of the interactions between organic species and the metallic support. Some emphasis was placed on the determination of the electronic energy levels at the organic/metal interface, which define the density of states (DOS) as well as the electrochemical properties of the scitation.org/journal/jcp hybrid system. The chemistry of the gold surface is of fundamental importance in material- and nanoscience.. The chemistry of the gold surface is of fundamental importance in material- and nanoscience.1–7 In this context, the interactions between organic molecules and gold nanoparticles have been found highly dependent on the size/shape of the metallic surface.. Several works sought to elucidate the physics at play at the interface by studying the adsorption of organic molecules on the gold metallic surface.. The understanding of the adsorption processes involves the correct description of the interactions between organic species and the metallic support.. Some emphasis was placed on the determination of the electronic energy levels at the organic/metal interface, which define the density of states (DOS) as well as the electrochemical properties of the scitation.org/journal/jcp hybrid system. The electronic structure of the interface is of interest to understand the transition from a molecular localized regime to a hybrid organic/metal semiconducting regime.
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