Chemisorption of iodine on Ag(110): a density-functional theory approach

The adsorption of iodine atom (I) on Ag(110) surface modeled by two-layer Agm+n(m,n) clusters has been studied by means of B3-LYP density-functional method. The effects of basis set and cluster size were tested. It is found that the adsorption properties are less sensitive to geometry than to basis set. The adsorption energy of I is found to converge after the coordination number of the Ag atoms forming the adsorption sites reaches its maximum. This determination allows us to extrapolate the adsorption properties of the iodine/Ag(110) surface from those of iodine/silver clusters. As a result, Ag16(8,8) and Ag21(12,9) are chosen to model four possible adsorption sites (long and short bridges, hollow and top) of Ag(110). The results show that the short bridge site is the most preferred for iodine adsorption, followed by top, hollow and long bridge sites. The present results about the effect of the adsorption of I atom on Ag(110) surface also provide a sound theoretical basis for the understanding of the role of I in heterogeneous catalysis.