Unveiling the structural and electronic properties of the neutral and anionic gallium sulfide clusters (original) (raw)

2013, Structural Chemistry

The structural and electronic properties of the neutral gallium sulfide (GaS 2 , Ga 2 S 2 , GaS 4 , and Ga 2 S 4) clusters along with their anionic counterparts have been investigated systematically using the density functional theory, the second-order Møller-Plesset perturbation theory (MP2), and coupled cluster singles and doubles, including noniterative triples [CCSD(T)] with the 6-311?G(2df) basis set. At the CCSDT(T)//MP2 level, the lowest-energy configurations of the gallium sulfides prefer to be cyclic (GaS 2), linear (GaS 2-), kite shape with a thiozonide unit (GaS 4 and GaS 4-), rhombic (Ga 2 S 2 and Ga 2 S 2-), and planar with two sulfur atoms in a terminal position (Ga 2 S 4 and Ga 2 S 4-) geometries. In the gallium-sulfur binary clusters considered in this study, the neutral and anionic ground-state geometries prefer the planar structures with alternation of gallium and sulfur atoms. All the neutral clusters, with the exception of Ga 2 S 2 , possess high electron affinities, which range from 3.51 to 3.64 eV at the CCSDT(T)//MP2 level. A sequential addition of a sulfur atom to the Ga 2 S n (n = 1-3) system increases the charge transfer from gallium atoms to sulfur atoms, the adiabatic electron affinity, and the HOMO-LUMO gap. The sufficiently large HOMO-LUMO gaps ensure the stability of these gallium sulfide clusters. The Ga 2 S 4 ? Ga 2 S 2 ? S 2 process is the most thermodynamically favored toward dissociation.