Sodalite framework modelling

With E and d as constants, equation 8 relates how the unit cell parameter is dependent on the p cage contents which determine c ). Another useful parameter needed in modelling sodalite framework and which varies with ao and ( ) is the angle ZTOT. From the coordinates of the special positions of adjacent T atoms, corresponding T...T distances can be worked out hence ZTOT ... 

SODALITE RELATED STRUCTURES AND OTHER FRAMEWORK MODELLING METHODS... 

The distribution of cations in a hydrated zeolite is mainly controlled by their sizes and can be described by a statistical model. In the dehydrated state, most of the cations are located on the intraframework sites their occupancies are governed by mutual repulsions and cation—framework interactions [1]. By which, the environments of the framework silicon atoms and their corresponding ssi NMR spectra are affected [2,3]. The chemical shift and lineshape of Si NMR have been found to depend on the nature and the distribution of cations in the small sodalite and double hexagonal prism (D6R) cavities of the dehydrated Y zeolites [3] The irreversible migration of La3 ions from the supercages to the small sodalite and/or D6R cavities by... 

B. Beagley, J. O. Titiloye, Modeling the Similarities and Differences between the Sodalite Cages (Beta-Cages) in the Generic Materials - Sodalite, Zeolites of Type-A, and Zeolites with Faujasite Frameworks Struct. Chem. 1992, 3, 429-448. 

In the early 1990s, Nicholas and coworkers proposed an MM force field for modeling siliceous zeolites. In their model the framework steric energy was described as a sum of a harmonic Si-O bond term, O-Si-O and Si-O-Si angle bending terms, and an Si-O-Si-0 dihedral angle term. The Lennard-Jones (12-6) and Coulombic terms represented nonbonded interactions. Their force field was successfully applied for calculation of the structures and infrared spectra of the siliceous sodalite and silicalite lattices. ... 

All modelling requires an acceptable theoretical starting point. The fundamental equations which are common to all sodalite models are presented and their relationship with the zeolite framework is discussed. Natural sodalite has an ordered structure with its T atoms (T=Al,Si) distinguished and situated on specific A1 and Si sites and a Si/Al ratio of 1. The structure has the symmetry of the cubic space group P43n. To develop a model... 

Table 5. Transformation of the fully expanded sodalite model into zeolite A framework with regular tetrahedra...

Table 7. Transformation of anhydrous sodalite model into idealised faujasite framework ...

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