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 A gm+n(m,n) clusters has been studied by means of B3-LYP density-functional m ethod. The effects of basis set and cluster size were tested. It is found t hat 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. T his determination allows us to extrapolate the adsorption properties of the iodine/Ag(110) surface from those of iodine/silver clusters. As a result, Ag-16(8,8) and Ag-21(12,9) are chosen to model four possible adsorption sit es (long and short bridges, hollow and top) of Ag(110). The results show th at the short bridge site is the most preferred for iodine adsorption, follo wed by top, hollow and long bridge sites. The present results about the eff ect of the adsorption of I atom on Ag(110) surface also provide a sound the oretical basis for the understanding of the role of I in heterogeneous cata lysis. (C) 2000 Published by Elsevier Science B.V. All rights reserved.