THE POTENTIAL OF MEAN FORCE ON HALIDE-IONS NEAR THE CU(100) SURFACE

This paper reports an investigation of the phenomenon of specific adso rption of halide ions on a Cu(100) surface using Monte Carlo simulatio ns. The system was modeled by considering each ion in a water lamina p laced between two copper walls. The potentials used in simulations wer e constructed by fitting to results of quantum calculations. The solve nt contribution to the potential of mean force (pmf) was calculated fo r each of the four halide ions using the free energy perturbation meth od. Given the difficulty of finding a reliable ion-metal potential, se veral alternatives, representing extremal models, were tested in combi nation with the solvent mean force on the ions, F-, Cl-, Br- or I-. Th e results for the pmf on an ion near the metal surface are discussed i n the light of the experimental data available. The sensitivity of the results to the type of ion-metal potential used in the simulations is stressed. (C) 1998 Elsevier Science S.A. All rights reserved.