Ab initio relativistic pseudopotential study of small silver and gold sulfide clusters (M2S)n, n=1 and 2

Abstract

The ab initio model potential method with the spin-free relativistic scheme by eliminating small components Hamiltonian Molecular density functional calculations in the regular relativistic approximation: Method, application to coinage metal diatomics, hydrides, fluorides and chlorides, and comparison with first-order relativistic calculations Small semiconductor silver and gold sulfide clusters (Ag 2 S) n and (Au 2 S) n , nϭ1,2, are studied by valence ab initio calculations with the inclusion of electron correlation at the second-order perturbation theory ͑MP2͒ and coupled-cluster ͓CCSD and CCSD͑T͔͒ levels. Various relativistic and nonrelativistic pseudopotentials are employed to describe the effects of core electrons. Correlation and relativistic effects are essential in determining the geometry and relative stability of monomer and dimer structures. Relativistic effects result in a notable decrease in the calculated interatomic distances, which is especially significant in the case of gold sulfide structures ͑up to 10%͒. Correlation effects markedly increase the stability of compact structures with an increased number of relatively short M...M contacts ͑M...M distances of about 280-330 pm͒. Excluding the correlation of lower-lying valence orbitals ͑sulfur 3s and silver 4d or gold 5d) results in completely opposite predictions. This fact suggests that the effects of d -d and d-outer valence ͑metal ns and sulfur 3p) electron correlation give rise to attractive short-range interactions of intramolecular van der Waals type, which determine the increased stability of more compact cluster structures. However, large-core pseudopotentials strongly exaggerate this effect in the case of gold and give results rather different from those obtained with more valid and accurate small-core pseudopotentials. It is shown that the reason for this deficiency lies in the nature of pseudopotentials themselves rather than in basis-set shortcomings. The atomization and dissociation energies, equilibrium geometrical parameters, dipole moments, and Mulliken populations are calculated and discussed.

Synthesis and anticancer properties of gold(I) and silver(I) N-heterocyclic carbene complexes

“…Carbonegold bond distances of 2.011(5) Å and 2.024(5) Å were observed for 5 and were similar to those of 6 observed at 2.001(4) Å and 2.028(4) Å. These distances were shorter in comparison with the corresponding silver analogs 3 with 2.073 (3) Å and 2.077(3) Å and 4 with 2.075(5) Å and 2.074(5) Å, an observation consistent with relativistic effects that make gold smaller than silver [38]. Both goldeNHC complexes and their silver precursors have carbonemetalecarbon bond angles close to linearity.…”

Reaction of Au(111) with Sulfur and Oxygen: Scanning Tunneling Microscopic Study

“…This demonstrates that the Au-S bond is strong enough to drive the corrosion of Au. Indeed, stable gold sulfide clusters ((Au 2 S) n , n = 1, 2) have been proposed to form based on ab initio calculations [43].…”

Density Functional Study of Small Neutral and Charged Silver Cluster Hydrides

“…E-mail: knfan@ fudan.edu.cn. Phone and fax: 86-21-65643977.ZO -Ag n + + H 2 f Ag n -H + ZOH ZO -Ag n + + CH 4 f Ag n -H + ZO δ -CH 3 δ+AgH -, Ag 2 H -, HAgH -, and HAg 2 H -, including three additional polarization basis functions (optimized for CCSD) (f, 2.54, 0.73; g, 1.58) and two additional diffuse basis functions (f, 0.2; g, 0.5) with the LANl2DZ basis set for Ag 17. The calculated binding energies are just 0.02-0.03 eV larger than the results calculated without the diffuse and polarization basis functions.…”