Parametrization of the Fe-Owater cross-interaction for a more accurate Fe3O4/water interface model and its application to a spherical Fe3O4 nanoparticle of realistic size.

The accurate description of iron oxides/water interfaces requires reliable force field parameters that can be developed through comparison with sophisticated quantum mechanical calculations. Here, a set of CLASS2 force field parameters is optimized to describe the Fe-Owater cross-interaction through comparison with hybrid density functional theory (HSE06) calculations of the potential energy function for a single water molecule adsorbed on the Fe3O4 (001) surface and with density functional tight binding (DFTB+U) molecular dynamics simulations for a water trilayer on the same surface. The performance of the new parameters is assessed through the analysis of the number density profile of a water bulk (12 nm) sandwiched between two magnetite slabs of large surface area. Their transferability is tested for water adsorption on the curved surface of a spherical Fe3O4 nanoparticle of realistic size (2.5 nm).