Classical Polarizable Force Field for Clays: Pyrophyllite and Talc

We develop a classical polarizable force field for clays based on the polarizable ion model (PIM), focusing on two neutral clays: pyrophyllite and talc. The full set of parameters of the force field is determined from density functional theory calculations using maximally localized Wannier functions with a force- and dipole-optimization procedure. Simulation results for our new polarizable force field (PIM) are compared to the state-of-the-art nonpolarizable flexible force field (ClayFF) to assess the importance of taking polarization effects into account for the prediction of structural properties. This new force field is validated by comparing the detailed structure of the two minerals against X-ray data. Introducing polarization allows for a good transferability and better agreement with the experimental data, in particular for the subtle orientational deformation of the layers.