| Abstract
| - A new, transferable classical force field potential for titanosilicate ion-exchange materials is reported. Plane-wave pseudopotential density functional theory (DFT) simulations are used to compute partial charges, wherethe atomic boundaries are partitioned through the Wigner−Seitz approach. The repulsion−dispersioninteractions are modeled with a 12-6 Lennard-Jones potential. The force field is parametrized with the acid-exchanged titanosilicate and transferred to the sodium-, cesium-, and strontium-exchanged titanosilicates andtheir niobium-substituted counterparts. Grand canonical Monte Carlo simulations are conducted to computethe sorptive properties of water in the acid-exchanged titanosilicate. Excellent agreement of the saturatedwater loading, positions, and occupancies with experimental neutron diffraction results is observed, while theadsorption energies at low water loading match DFT calculations. In transferring the force field to the sodium-,cesium-, and strontium-exchanged titanosilicates, canonical replica exchange Monte Carlo simulations areused to enhance cation sampling. The Wigner−Seitz force field parametrization effectively predicts theadsorption properties and provides a molecular-scale picture of the origins of titanosilicate selectivity in thesematerials. Overall, the methodology for translating electronic structural information derived from DFTcalculations to classical force field based simulations can easily be extended to alternative crystalline materialssuch as zeolites and clays.
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