Atomic interaction guest-framework

Furthermore, the lone pairs at (3b)Ge atoms are visualized by the four ELI attractors oriented toward the vacancy position (Fig. 2.10, bottom). The distribution of ELI-D in the inner shells of the Ge atoms is spherical, indicating that, as expected, the electrons of the inner shells do not participate in valence interactions. The striking feature of the ELI-D distribution around the Ba atoms is the missing sixth shell. This suggests charge transfer to the framework and is in agreement with the idea of ionic guest-framework interaction (Fig. 2.10, middle left). The... 

Cation exchanged zeolites are successfully applied as catalysts or selective sorbents in separation technologies. " For both catalytic and sorption processes a concerted action of polarizing cations and basic oxygen atoms is important. In addition, transition metal cation embedded in zeolites exhibit peculiar redox properties because of the lower coordination in zeolite cavities compared to other supports." " Therefore, it is important to establish the strength and properties of active centers and their positions in the zeolite structure. Various experimental methods and simulation techniques have been applied to study the positions of cations in the zeolite framework and the interaction of the cations with guest molecules.Here, some of the most recent theoretical studies of cation exchanged zeolites are summarized. 

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