Yongfang Zhao

Bonding analysis for NgMOH (Ng=Ar, Kr and Xe; M=Cu and Ag)

The structures and stabilities of a new class of species, noble-gas–coinage-metal hydroxides NgMOH (Ng  = Ar, Kr and Xe; M  = Cu and Ag), are investigated at the MP2 theoretical level. All species are found to be in Cs symmetry with an approximate linear Ng–M–O moiety. The noble-gas–coinage-metal bond lengths are in the range of the respective covalent and van der Waals limits, showing a different degree of approach to the former along the series Ar–Kr–Xe for Ng–Cu and Ng–Ag bonds, respectively. The dissociation energies of noble-gas–coinage-metal bonds are relatively large as compared to the van der Waals complexes. Besides the charge-induced dipole contribution, other effects  – higher-order charge-induction energies, dispersion interaction, etc., should be considered to explain the noble-gas–coinage-metal bonding mechanism. The present results suggest that the title species are stable enough to be prepared experimentally.

Ab initio study of small coinage metal telluride clusters AunTem (n, m = 1, 2)

The geometries of the most stable isomers of gold telluride systems AuTe, Au2Te, and AuTe2 are determined using the MP2 method. The aspect of gold—telluride interaction, the electron correlation, and relativistic effects on geometry and stability are investigated at the MP2 and CCSD(T) theoretical levels. The results show that the electron correlation and relativistic effects are responsible not only for gold—gold attraction but also for additional gold—telluride interaction. The gold—telluride interaction is strong enough to modify the known pattern of bare gold clusters. Both effects are essential for determining the geometry and relative stability of this type of systems.

Ab initio pseudopotential study of M2As− and M2Br+ (M = Cu, Ag, Au)

The equilibrium geometries and the vibration frequencies of M2As− and M2Br+ (M = Cu, Ag, Au) are calculated at the Hartree–Fock (HF) and the second-order Moller–Plesset (MP2) levels with pseudopotentials. The calculated results indicate that the species have a bent structure (C2v). The electron correlation corrections on the geometrical structure are investigated at the MP2 level, the bond angles are reduced by 10°–20° for considered species. The electron correlation effects on the geometry of the Au2As− are studied particularly at MP2, MP3, MP4, CCSD and CCSD(T) levels. Comparing the species containing Ag and Au, the relativistic effects slightly short the bond lengths of the species. The bonding possibility of the Au2As− is predicted.

Geometrical and electronic structures of the SnnCl and SnnCl- (n = 1-6) clusters

Theoretical studies of the structures of Sn n Cl and Sn n Cl− (n = 1–6) clusters have been carried out using density functional theory methods. The geometric structure of each unit is optimized at the B3LYP level, employing the LANL2DZpd for tin and DZP++ for chlorine basis sets. The resulting total energies, fragmentation energies and equilibrium geometries of chlorine–tin clusters are presented and discussed, together with natural populations and natural electron configurations. The impact on internal electron transfer between the (Sn n ) subsystem and Cl atom in Sn n Cl− (Sn n Cl) clusters is investigated. In addition, theoretical results for the electron affinities of Sn n Cl (n = 4–6) clusters are in good agreement with experimental results available.

An Ab initio pseudopotential study of MnPo (M = Cu, Ag, Au; n = 1, 2) systems

The small coinage-metal polonium compounds MPo and M2Po, (M = Cu, Ag, Au) are studied at Hartree–Fock (HF), second-order Moller–Plesset perturbation theory (MP2), and coupled cluster method CCSD(T) levels using relativistic and non-relativistic pseudopotentials. The calculated geometries indicate that the M2Po (M = Cu, Ag, Au) systems have bent structures of ~64° angles. Electron correlation corrections to the bond length M–Po are extremely small, but to the bond angle M–Po–M are significant; in general, it was reduced from 86° to 64°. Relativistic effects on bond angle are small, but on bond length are distinct. Both electron correlation effects and relativistic effects are essential to determine the geometry and relative stability of the systems. It can be predicted that Au2Po is relatively stable compared with Ag2Po.

Ab Initio Study on Structures and Vibrational Spectra of M+(H2O)Ar2 (M = Cu, Au)

Previous investigations have shown that it is difficult to acquire the infrared (IR) spectra of M+(H2O) (M = Cu, Au) using a single IR photon by attaching an Ar atom to M+(H2O). To explore whether the IR spectra can be obtained using the two Ar atoms tagging method, the geometrical structures, IR spectra and interaction energies are investigated in detail by ab initio electronic structure calculations for M+(H2O)Ar2 (M = Cu, Au) complexes. Two conceivable isomeric structures are found, which result from different binding sites for two Ar atoms. CCSD(T) calculations predict that two Ar atoms are most likely to attach to Cu+ for the Cu+(H2O)Ar2 complex, while the Au+(H2O)Ar2 complex prefers the isomer in which one Ar atom attaches to an H atom of the H2O molecule and the other one is bound to Au+. Moreover, the calculated binding energies of the second Ar atom are smaller than the IR photon energy, and so it is possible to obtain the IR spectra for both Cu and Au species. The changes in the spectra caused by the attachment of Ar atoms to M+(H2O) are discussed.

Ab Initio Study of Structure and Stability of M2Al2 (M = Cu, Ag, and Au) Clusters

Coinage metal aluminium clusters M2Al2 (M = Cu, Ag, and Au) were studied by Hartree–Fock (HF) and second-order Moller–Plesset perturbation theory (MP2) with pseudopotentials. It was found that the butterfly structure with C2v (1A1) symmetry is more stable than the planar structure, and Au2Al2 is the most stable of the title species. The binding energies and the highest occupied molecular orbital and the lowest unoccupied molecular orbital (HOMO–LUMO) gap are evaluated, which indicates that doping clusters M2Al2 are more stable than the pure clusters M4 (M = Cu, Ag, and Au). Electron correlation and relativistic effects stabilize the present species.

Theoretical investigation of stabilities and interactions of AuNenZ (n = 1-3, Z = -1, 0, +1) clusters

The structures and stabilities of (n = 1–3, Z = −1, 0, +1) clusters have been investigated at CCSD(T) theoretical level. It is shown that the cations have compact structures and enhanced stabilities compared with anions and neutrals. The nature of the interaction is explored using the natural bond orbital, population and electron density analysis.