A density functional theory study on the Ag n H (n = 1–10) clusters

Abstract

Density functional GGA-PW91 method with DNP basis set is applied to optimize the geometries of Ag n H (n = 1-10) clusters. For the lowest energy geometries of Ag n H (n = 1-10) clusters, the hydrogen atom prefers to occupy the two-fold coordination bridge site except the occupation of single-fold coordination site in AgH cluster. After adsorption of hydrogen atom, most Ag n structures are slightly perturbed and only the Ag 6 structure in Ag 6 H cluster is distorted obviously. The Ag-Ag bond is strengthened and the strength of Ag-H bond exhibits a clear odd-even oscillation like the strength of Au-H bond in Au n H clusters, indicating that the hydrogen atom is more favorable to be adsorbed by odd-numbered pure silver clusters. The adsorption strength of small silver cluster toward H atom is obviously weaker than that of small gold cluster toward H atom due to the strong scalar relativistic effect in small gold cluster. The pronounced odd-even alternation of the magnetic moments is observed in Ag n H systems, indicating that the Ag n H clusters possess tunable magnetic properties by adsorbing hydrogen atom onto oddnumbered or even-numbered small silver cluster.

Probing the structural and electronic properties of AgnH− (n = 1–3) using photoelectron imaging and theoretical calculations

“…4, there are two stable structures for Ag 2 H − and Ag 2 H, respectively. The C 2v triangular structure of Ag 2 H predicted in earlier theoretical studies 21,22 turned out to have imaginary frequencies in our calculations. For Ag 2 H − , the lowest energy structure in our results has C ∞ν geometry.…”

“…They found that the bridge sites were the most favorable binding positions for hydrogen atom in all cationic, most of the neutral and the larger anionic clusters, while for Ag n H (n = 3) and Ag n H − (n ≤ 4), the top sites of silver clusters were preferred by hydrogen atom. Very recently, Kuang et al 22 investigated the geometries of Ag n H (n = 1-10) using GGA-PW91 DFT method and the results indicated that the hydrogen atom binded stronger on the clusters containing odd number silver atoms, and tended to occupy the two-fold bridge sites. In spite of all those theoretical efforts, structural and electronic characters of silver hydrides were still obscure due to some inconsistent conclusions and the lack of experimental evidences.…”

Benchmarking Density Functional Based Tight-Binding for Silver and Gold Materials: From Small Clusters to Bulk

“…This has been achieved essentially either via wave function based methods for the characterization of small clusters − or via density functional theory (DFT) for bulks, surfaces, and middle-size clusters. In particular, the structure of neutral, cationic, and anionic clusters with N up to ∼20–25 has been the subject of numerous DFT investigations for both silver ,− and gold. − Nevertheless, although DFT can handle small to middle-size aggregates, the resulting properties show significant dependence over the functional, and it is only recently that the use of accurate functionals such as revTPSS, M06, , SOGGA, or RPA methods seems to have lifted the uncertainties about the structural and electronic features of even small-size clusters. For instance, the 2D–3D transition in gold clusters has been in debate for some time and only recent theoretical studies provided results in agreement with the experimental data .…”

CO Oxidation by Molecular and Atomic Oxygen on Ag(100): A Density Functional Theory Study

“…All calculations were performed using the suite program of Gaussian 09 . The pw91pw91 hybrid exchange–correlation functional , was used, which has shown good reliability and accuracy in previous reports. − For silver, the effective core potential (ECP) of Lanl2 combined with the DZ basis set was adopted, − while for O and C atoms, the full electron basis set of 6-31G­(d) was employed. − All stationary points on the potential energy surface (PES) were verified by calculated vibrational frequencies at the same theoretical level as used in the geometry optimization. To locate a transition state (TS), a relaxed PES scan was carried out first to find the structure with the highest energy on the reaction path.…”