Solvation of N3- at the water surface: the polarizable continuum model approach.

We present a new quantum mechanical model to introduce Pauli repulsion interaction between a molecular solute and the surrounding solvent in the framework of the Polarizable Continuum Model. The new expression is derived in a way to allow naturally for a position-dependent solvent density. This development makes it possible to employ the derived expression for the calculation of molecular properties at the interface between two different dielectrics. The new formulation has been tested on the azide anion (N3-) for which we have calculated the solvation energy, the dipole moment, and the static polarizability at the interface as a function of the ion position. The calculations have been carried out for different ion-surface orientations, and the results have also been compared with the parallel electrostatic-only solvation model.