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Density functional theory study of Au n ( n = 1–5) clusters supported on montmorillonite
Author(s) -
BrionesJurado Claudia,
de la Mora Pablo,
AgacinoValdés Esther
Publication year - 2012
Publication title -
international journal of quantum chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.484
H-Index - 105
eISSN - 1097-461X
pISSN - 0020-7608
DOI - 10.1002/qua.24308
Subject(s) - montmorillonite , density functional theory , nucleation , cluster (spacecraft) , atom (system on chip) , crystallography , adsorption , fermi level , chemistry , transition metal , supercell , density of states , gold cluster , materials science , computational chemistry , physics , condensed matter physics , organic chemistry , computer science , embedded system , catalysis , programming language , thunderstorm , quantum mechanics , meteorology , electron
The adsorption and nucleation of gold clusters Au n ( n = 1–5) on montmorillonite (MMT) is studied using the density functional theory. All the calculations were performed using the full‐potential linearized augmented‐plane‐wave method as implemented in the WIEN2k code. We constructed a MMT supercell of formula Si 16 Al 6 Mg 2 O 40 (OH) 8 containing four unit cells and the first moments of the nucleation process were studied by adding the gold atoms one by one on the MMT. The results show that the interaction energies between the gold clusters and the MMT are negative indicating that the Au n –MMT complexes are stable. In the Au n –MMT systems ( n = 3–5), two gold atoms maintain the coordination with basal oxygens and the AuO distance was about 2.0–2.3 Å. The AuAu average distance is 2.6 Å in the supported gold clusters. The formation of the second layer of gold atoms occurs upon the arrival of the third gold atom. We are reporting that the transition of 2D → 3D gold cluster structures is located from Au 3 to Au 4 on MMT. The total density of states of clusters Au, Au 2 , Au 3 , Au 4 , and Au 5 on MMT allows us to affirm that (i) gold atoms are the main contributors to the states closest to the Fermi level and (ii) in Au 4 –MMT and Au 5 –MMT systems, the main contributors to the states closest to the Fermi level are the most external gold atoms, and therefore these atoms are probably the most susceptible to interact with adsorbates and the most active sites. Odd–even oscillations in the values of the energy gap and interaction energy were found: the odd‐numbered supported clusters, Au 3 and Au 5 , have larger energy gaps and more negative interaction energies. © 2012 Wiley Periodicals, Inc.