Adsorption of water on the MgO(001) surface

Physisorption of water on the MgO(001) surface has been investigated. New p otentials between water and Mg2+ and between water and O2- have been constr ucted using intermolecular perturbation theory. The new potentials give an interaction energy of -65.4 kJ mol(-1) for isolated molecules on the surfac e, corresponding to a desorption enthalpy of 55 kJ mol(-1) at 220 K, in goo d agreement with an experimental estimate. Several different minimum-energy monolayer structures were investigated at a coverage of one water molecule per MgO unit. It was found that a pg(2 x 1) structure had a slightly lower equilibrium energy than the pg(3 x 2) structure found experimentally at ab out 200 K. It is suggested that differences in vibrational energy could acc ount in part for the discrepancy between theory and experiment. (C) 1999 El sevier Science B.V. All rights reserved.