A Transferable Force Field for Predicting Adsorption and Diffusion of Hydrocarbons and Small Molecules in Silica Zeolites with Coupled-Cluster Accuracy

We present a transferable force field for hydrocarbons (linear
and branched olefins and paraffins) and small adsorbates (CO2, O2, N2, and H2O) in pure silica
zeolites. The fitting procedure is based on adsorbate–adsorbent
interaction energies obtained from periodic density functional theory
calculations and corrected using coupled-cluster methods applied to
small clusters. The fitting approach aims at accurate prediction of
both adsorption and diffusion properties by using sets of configurations
that sample adsorption sites and intracrystalline hopping transition
states. The quality of the force field is assessed for a wide range
of adsorbates in zeolites with different topologies, showing good
agreement between theoretical predictions and a range of experimental
measurements of adsorption and diffusion.