Evaluation of clay force fields for different applications
Clay minerals are hydrous-layered aluminum silicates usually in the form of ultrafine (micro to nanoscale) crystallites consisting of tetrahedral (T) silicate and octahedral (O) oxyhydroxide sheets. The ratio of these sheets can be either 1:1 (T-O) or 2:1 (T-O-T). By changing the anions in the tetra or octahedral (usually, Al for Si and Mg for Al) a wide range of clay mineral structures and compositions can be obtained. Clay minerals possess several attractive properties for industrial applications such as high adsorption ability, high internal surface area, high cation exchange capacity, chemical inertness etc. Because of these properties, clay minerals are applied in several areas of industry. However, to discover new possible applications of these materials a molecular understanding of the underlying thermodynamic, kinetic and ion-exchange phenomena (swelling, adsorption etc.) is of great importance. One way to obtain such insights is using state-of-the-art molecular simulation techniques (Monte Carlo, Molecular Dynamics, Free energy calculations etc.) which are based on calculating the energy of the given system by using optimized and fitted force field parameters. However, the transferability of these parameters for given applications is not straightforward and requires thorough investigation. In our research group, the level of performance and applicability of various clay force fields parameters are investigated for several applications (adsorbents, membranes etc.) of clay minerals. Ultimately, we would like to give a better overview about the applicability of the available clay models (such as the new ClayFF force field parameters).