Probing the geometries, relative stabilities, and electronic properties of neutral and anionic Ag_nS_m (n+m≤7) clusters

摘要

The geometry structures, relative stabilities, and electronic properties of neutral and anionic Ag_nS_m (n+m≤7) clusters have been investigated systematically by means of density function theory (DFT). The results of geometry optimization show that the most stable configurations of binary Ag_nS_m~(0/-) clusters have an early appearance of 3D structure at n=3, m=1, differing from those of pure silver and sulfur clusters.Moreover, the ground-state structures prefer low spin multiplicity (singlet or doublet) except for S_2, Ag_2S_3, Ag_2S_4, Ag_4S_3, and Ag_2S_5. The calculated electron detachment energies (both vertical and adiabatic) are in good agreement with experimental data. This further lends considerable credence for the lowest-energy structures and the chosen computational method. By calculating the binding energies, fragmentation energies, second-order difference of energies and HOMOLUMO energy gaps of neutral and anionic Ag_nS_m clusters, the relative stability and electronic property as a function of cluster size are discussed in detail. Further, in order to understand the nature of the bond in doped clusters and pure clusters, we have performed the contour maps of their HOMOs and analyzed their composition.