Classical Polarizable Force Field To Study Dry Charged Clays and Zeolites

We extend the classical Polarizable Ion Model (PIM) to charged clays. We focus on Na-, Ca-, Sr-, and Cs-montmorillonite with two types of structures for the octahedral sheet: trans- and cis-vacant. The full set of parameters of the force field is determined by density functional theory calculations, using maximally localized Wannier functions with a force- and dipole-optimization procedure. Simulation results for our polarizable force field are compared with the state-of-the-art nonpolarizable flexible force field named Clay Force Field (ClayFF) to assess the importance of taking polarization effects into account for the prediction of structural properties. This force field is validated by comparison with experimental data. We also demonstrate the transferability of this force field to other aluminosilicates by considering faujasite-type zeolites and comparing the cation distribution for anhydrous Na, Ca, and Sr Y (and X) faujasites predicted by the PIM model and with experimental data.