Interaction of S, SH and H2S with Ag(100)

A theoretical study of the interaction of S, SH, and H2S with Ag( 100) 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 H,S on Ag( 10 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 H-2 and adsorbed S is predicted to be exothermic by 32.6 kcal mol(-1). (c) 2005 Elsevier B.V. All rights reserved.