Interaction of S, SH and H2S with Ag(1 0 0)

A theoretical study of the interaction of S, SH, and H2S with Ag(1 0 0) has been carried out using ab initio configuration interaction (CI) theory. The adsorbate–surface system is described by an embedded cluster model. It is found that S adsorption at the fourfold hollow site is the most stable with an adsorption energy of 77.2 kcal mol−1. For SH adsorption, atop, bridge and hollow sites have nearly identical adsorption energies, 43.1 kcal mol−1, 42.9 kcal mol−1 and 42.7 kcal mol−1, respectively, but very different equilibrium geometries. Adsorption energies of H2S on Ag(1 0 0) range from 3.2 kcal mol−1 to 4.8 kcal mol−1, with the atop site favored by 1.4 kcal mol−1. Dissociation of H2S to desorbed H2 and adsorbed S is predicted to be exothermic by 32.6 kcal mol−1.