Computational Studies of Nonstoichiometric Sodium Auride Clusters

Abstract

The molecular structures of low-lying isomers of anionic and neutral sodium auride clusters have been studied computationally at the second-order Møller-Plesset perturbation theory level using quadruple-ζ basis sets augmented with a double set of polarization functions. The first vertical detachment energies were calculated at the Møller-Plesset level as the energy difference between the cluster anion and the corresponding neutral cluster. The photodetachment energies of higher-lying ionization channels were calculated by adding electronic excitation energies of the neutral clusters to the first vertical detachment energy. The excitation energies were calculated at the linear response approximate coupled-cluster singles and doubles level using the anionic cluster structures. The obtained ionization energies for NaAu(-), NaAu(2)(-), NaAu(3)(-), NaAu(4)(-), Na(2)Au(2)(-), Na(2)Au(3)(-), Na(3)Au(3)(-), and Na(2)Au(4)(-) were compared to values deduced from experimental photoelectron spectra. Comparison of the calculated photoelectron spectra for a few energetically low-lying isomers shows that the energetically lowest cluster structures obtained in the calculations do not always correspond to the clusters produced experimentally. Spin-component-scaled second-order Møller-Plesset perturbation theory calculations shift the order of the isomers such that the observed clusters more often correspond to the energetically lowest structure, whereas the spin-component-scaled approach does not improve the photodetachment energies of the sodium aurides. The potential energy surface of the sodium aurides is very soft, with several low-lying isomers requiring an accurate electron correlation treatment. The calculations show that merely the energetic criterion is not a reliable means to identify the structures of the observed sodium auride clusters; other experimental information is needed to ensure a correct assignment of the cluster structures. The cluster structures of nonstoichiometric anionic sodium aurides have been determined by comparing calculated ionization energies for low-lying structures of the anionic clusters with experimental data.

Sodium–gold binaries: novel structures for ionic compounds from anab initiostructural search

“…A further motivation to study NaAu binary systems comes from the fact that previous results on clusters and thin-films [1,3,[13][14][15] hint at the existence of very different stoichiometries and coordinations. From the theoretical side, there are very few ab initio investigations of this family of compounds [16] and almost all the published calculations are devoted to NaAu clusters [3,14,15].…”

A density functional study of phosphorus-doped gold clusters: AunP− (n = 1–8)

“…7,8,73 Isomer 1 shows the same geometry as Au 3 S À , while the global minima of Au 3 X À (X ¼ Na, Mg, Al, Si) are similar to Isomer 3 of Au 3 P À ; additionally, these structures all vary from the low-lying isomers of pure Au 4 À . 7,8,38,[69][70][71][72][73][74] Au 4 P À . The low-lying isomers of Au 4 P À are shown in Tables 1 and S3 (ESI †).…”

The Uncertain Bond Energy of the NaAu Molecule: Experimental Redetermination and Coupled Cluster Calculations

“…In the last 15 years, the alkali-gold diatomics (MAu) have been studied computationally by a variety of methods: four-component density functional theory (DFT) for the entire series, , as well as for KAu to FrAu; DFT and CCSD(T) for LiAu through KAu; Dirac–Fock, four-component DFT, and CCSD(T) for CsAu; RI-MP2 and RI-MP2, SCS-MP2, and RI-CC2 for NaAu; DFT for NaAu. , These results indicate a distorted W trend of the dissociation energy along the alkali group, with minima at Na and Rb.…”