A METHOD FOR INCLUDING ENVIRONMENT POLARIZATION EFFECTS IN AB-INITIO CLUSTER EMBEDDED CALCULATIONS - APPLICATION TO THE WATER DEPROTONATIONOVER AN IDEAL AL-MGO SURFACE

A method to estimate the polarization contributions to the reaction en ergy in ab initio model potential embedded cluster calculations is rep orted. The method is developed in the framework of the theory of the e lectronic separability and makes use of a perturbational expansion of the interaction energy between the cluster and the environment. In a c lose way to that proposed by Hliwa, Barthelat and Malrieu to compute d ispersion energies, only the polarizabilities of the subunits involved in the environment description and the electric field created by the cluster in this region are needed. The method is tested in the study o f the deprotonation reaction over an ideal Al doped MgO(100) surface. By considering different size clusters, an excellent agreement between the variational and perturbational corrections due to the repolarizat ion of the environment is found.