Structures of neutral and anionic Au16 clusters revisited

Probing the structural, electronic, and adsorptive properties of Au16O2- clusters

Great progress has been made in O₂ adsorption on gold clusters. However, systematic investigations of O₂ adsorption on [Formula: see text] clusters have not been reported. Here, we present a systematic study of the structural, electronic, and adsorptive properties of [Formula: see text] clusters by density functional theory (DFT) calculations coupled with stochastic kicking method. Global minimum searches for [Formula: see text] reveal that exohedral derivatives are more favored. Furthermore, the obtained ground-state structure exhibits significant stability, as judged by its larger adsorption energy (1.16 eV) and a larger HOMO-LUMO gap (0.57 eV). The simulated photoelectron spectra (PES) of [Formula: see text] isomers will be instructive to identify the structures in future experiments. There are three interesting discoveries in the present paper: (1) O₂ undergoes chemical adsorption onto the parent [Formula: see text] clusters, but the amount of the adsorption energy is related to the parent [Formula: see text] clusters; (2) the process that O₂ undergoes dissociative adsorption onto the parent [Formula: see text] clusters is exothermic; (3) [Formula: see text] isomers show smaller X-A energy gaps than those of parent [Formula: see text] clusters, reflecting that their geometric and electronic structures are distorted remarkably due to dissociative adsorption of O₂.

Nonlocal effects on the structural transition of gold clusters from planar to three-dimensional geometries

Conventional density functional theory calculations heavily bias planar structures in gold clusters, failing to predict the structural transition from planar to three-dimensional geometries in experimentally detected gold species. Inspired by recent progress in calculating the defect energies of coinage metals with nonlocal effect-enhanced hybrid functionals, we have studied nonlocal effects in gold clusters. Although the hybrid functional was accurate for bulk gold, it heavily biased the planar structure for gold clusters. By including dispersive interactions into semilocal density functional calculations, we obtained an accurate vacancy formation energy of 0.72 eV for bulk gold along with the correct structural transition for gold clusters. The transition was found to occur at Au12 - for gold anions and at Au8 + for gold cations, agreeing very well with the experimental results. For neutral gold clusters, we found the transition to occur at Au10, indicating the need for experimental verification. The results show the importance of nonlocal effects in the study of gold clusters, calling for further comprehensive theoretical and experimental studies to evaluate nonlocal effects in Au and other precious metals.

New carbon allotropes with metallic conducting properties: a first-principles prediction

Combining density functional theory computation and the global minimum structural search, we have found new α-, β-, and δ-phographene carbon allotropes.

CO oxidation on Rh-doped hexadecagold clusters

Exploring the unique catalytic properties of gold clusters associated with specific nano-architectures is essential for designing improved catalysts with a high mass-specific activity.

Probing the structures of gold-aluminum alloy clusters AuxAly(-): a joint experimental and theoretical study

Besides the size and structure, compositions can also dramatically affect the properties of alloy nanoclusters. Due to the added degrees of freedom, determination of the global minimum structures for multi-component nanoclusters poses even greater challenges, both experimentally and theoretically. Here we report a systematic and joint experimental/theoretical study of a series of gold-aluminum alloy clusters, AuxAly(-) (x + y = 7,8), with various compositions (x = 1-3; y = 4-7). Well-resolved photoelectron spectra have been obtained for these clusters at different photon energies. Basin-hopping global searches, coupled with density functional theory calculations, are used to identify low-lying structures of the bimetallic clusters. By comparing computed electronic densities of states of the low-lying isomers with the experimental photoelectron spectra, the global minima are determined. It is found that for y ≥ 6 there is a strong tendency to form the magic-number square bi-pyramid motif of Al6(-) in the AuxAly(-) clusters, suggesting that the Al-Al interaction dominates the Au-Au interaction in the mixed clusters. A closely related trend is that for x > 1, the gold atoms tend to be separated by Al atoms unless only the magic-number Al6(-) square bi-pyramid motif is present, suggesting that in the small-sized mixed clusters, Al and Au components do not completely mix with one another. Overall, the Al component appears to play a more dominant role due to the high robustness of the magic-number Al6(-) square bi-pyramid motif, whereas the Au component tends to be either "adsorbed" onto the Al6(-) square bi-pyramid motif if y ≥ 6, or stays away from one another if x < y < 6.

Structure identification of endohedral golden cage nanoclusters

The endohedral structures of MAu₁₆⁻ (M = Y, Zr and Nb) nanoclusters.

Superatom-atom super-bonding in metallic clusters: a new look to the mystery of an Au20 pyramid

Using the super valence bond model, a generalized chemical picture for the electronic shells of an Au20 pyramid is given. It is found that Au20 can be viewed to be a superatomic molecule, of which its superatomic 16c-16e core (T) is in D(3)S hybridization bonded with four vertical Au atoms for the molecule-like (TAu4) electronic shell-closure. Based on such a superatom-atom bonding model, TX4 (X = F, Cl, or Br) are predicted to be very stable. Such a superatom-atom T-Au/T-X bonding enriches the scope of chemistry.

Insight into the vertical detachment energy oscillation of Na(n)C60(-) clusters

We have performed a detailed density functional theory study on the structural and electronic properties of Na(n)C(60)(-) (n = 1-12) clusters. The calculated vertical detachment energies show good agreement with the experimental data, which confirms the 3p (n = 3p) oscillation rule. The oscillation can be attributed to the combination of the charge depletion distribution induced by removing electrons and the number of the sodium atoms in direct contact with the fullerene. Based on the structural and electronic properties, the Na atoms can be categorized into two groups, one is for the metal atoms directly bonded to the fullerene surface, and the other one is for those without bonding to the fullerene. The Na atoms in group one would donate electrons to both the fullerene and the Na atoms in group two. As the total number of the sodium atoms increases, the number of Na atoms in group one would continue increasing till the size n = 3p - 1 to meet a shoulder from n = 3p - 1 to n = 3p, which accounts for the maximum vertical detachment energy at the size of n = 3p as drawn from the detailed electronic property studies.