(335d) Trappe-Zeo: Transferable Potentials for Phase Equilibria Force Field for All-Silica Zeolites

The transferable potentials for phase equilibria (TraPPE) force field is extended to allow for the investigation of adsorption behavior in all-silica zeolites where the zeolite host is treated as a rigid framework.  The new TraPPE-zeo force field provides Lennard-Jones parameters and partial charges for the framework atoms.  As for other parts of the TraPPE force field, Lorentz-Berthelot combining rules are employed to determine the parameters for all cross interactions, making the TraPPE-zeo force field applicable to any sorbate compound as long as suitable Lennard-Jones parameters and partial charges are available to describe sorbate-sorbate interactions; a significant advantage over force fields that explicitly tabulate the individual cross interaction parameters.  The TraPPE-zeo force field is parameterized using a concurrent multi-dimensional fitting strategy to match a target set of experimental adsorption isotherms including n-alkanes, carbon dioxide, and ethanol as sorbates; that is, the TraPPE-zeo force field can treat the adsorption of non-polar, weakly polar, polar, and hydrogen-bonding compounds in a consistent manner.  High accuracy of adsorption isotherms is also found for a diverse set of validation compounds over a wide range of pressures and temperatures.