Polarizable force field for TiO2 based on the Drude oscillator model

Abstract

A polarizable force field has been developed for molecular dynamics simulations of titanium dioxide in an aqueous environment. The force field uses the standard functional form with an additional term accounting for polarizability, i.e., induction interaction, and has been derived exclusively from ab initio calculations by partitioning of electron density. Polarizability is described using the Drude oscillator model where each non-hydrogen atom is represented by two point charges connected by a harmonic potential. It is demonstrated that the force field provides a realistic description of the structure of anatase and rutile bulk materials from x-ray experiments. In addition, it is shown that, when combined with the popular SWM4-NDP polarizable water model, the force field describes the water structure at the titanium dioxide–water interface in agreement with results from ab initio molecular dynamics simulations. Importantly, our new model provides significant improvement of results for water differential adsorption enthalpy measured by calorimetry experiments compared to previous non-polarizable force field. The new force field allows for accurate simulations of titanium dioxide–aqueous interfaces for systems of a size of ∼105 atoms and simulation times up to the microsecond time scale.