Normal mode calculations of faujasite-type zeolite frameworks

Abstract

Normal mode calculations about the extended double six ring (D6R) subunit cluster model of Faujasite-type zeolites have been done by using the valence force field with reasonably adjusted force constants. We have studied four X, Y zeolites species varying in $M_f$(Al/Si+Al) values. The calculated characteristic frequencies of D6R mode ($\nu_{D6R}$) and the rate of change of $\ny$D6R with $M_f$(Al/Si+Al) values agree well with Flanigen``s experimental data, ; the experimental slope is -79 $cm^{-1}$, while the calculated slope is -82 $cm^{-1}$. Those are the improved results as compared to Blackwell``s theoretical study; his predicted slope is -94 $cm^{-1}$.